Systems and applications of lighter-than-air (lta) platforms

ABSTRACT

Innovative new methods in connection with lighter-than-air (LTA) free floating platforms, of facilitating legal transmitter operation, platform flight termination when appropriate, environmentally acceptable landing, and recovery of these devices are provided. The new systems and methods relate to rise rate control, geo-location from a LTA platform including landed payload and ground-based vehicle locations, and steerable recovery systems.

RELATED APPLICATIONS

This Application is a Divisional of U.S. patent application Ser. No.13/757,585 filed Feb. 1, 2013, which is a Divisional of U.S. patentapplication Ser. No. 12/099,004 filed Apr. 7, 2008, which is aDivisional of U.S. patent application Ser. No. 10/673,474 filed Sep. 30,2003, now U.S. Pat. No. 7,356,390, which is Continuation-In-Part of U.S.patent application Ser. No. 09/342,440 filed Jun. 29, 1999, now U.S.Pat. No. 6,628,941, and of U.S. patent application Ser. No. 10/129,666filed May 9, 2002, now U.S. Pat. No. 7,203,491; U.S. patent applicationSer. No. 10/129,666 is a National Stage of PCT/US02/12228 filed Apr. 18,2002, which claims benefit to U.S. Provisional Application No.60/284,799 filed Apr. 18, 2001; the contents of all of which areincorporated herein in their entirety by reference. This instantapplication is related to U.S. patent application Ser. No. 14/328,331filed Jul. 10, 2014, which is also incorporated herein in its entiretyby reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to unmanned lighter-than-air platformsoperating in the stratosphere and more particularly, their terminationand recovery.

BACKGROUND OF THE INVENTION

Unmanned lighter-than-air ballooncraft have been used for many years toperform tasks such as near space research, and meteorologicalmeasurements. Such ballooncraft have even carried payloads withinstrumentation that sometimes includes radio transmission capabilities.

Until recently, all communications satellites were located on one orbitcalled the geosynchronous arc, which is located 22,300 miles above theEarth's equator. Since international treaties required satellites to bespaced two degrees apart, there were only 180 sites on geosynchronousorbit. An optimally-designed three-stage chemical rocket typically mustbe 94% propellant at launch to reach geosynchronous orbit, which, afterallocating about 5.6% of the weight for the rocket, only leaves about0.4% of the initial launch weight for the satellite. To put this inperspective, a typical 3,000 lb. automobile with the same performancewould only be able to carry one 200 lb. person, would need an8,400-gallon fuel tank, and would be junked after one trip! Finally,although the NASA space shuttle can service a few very low orbitsatellites at great expense, most satellites cannot be serviced orupgraded after being launched.

Currently, since there are a limited number of sites on thegeosynchronous orbit, geosynchronous satellites are growing in size andperformance, now being able to broadcast television signals directly tohomes. Recently, additional satellite networks have been deployed thatdo not require a geosynchronous orbit. All of these new networks havelaunched smaller communication satellites into much lower orbits wherethere are an unlimited number of sites. Because the satellites requiredfor a network are more numerous and because the satellites are smaller,up to 8 satellites per rocket have been launched. Although satelliteshave become smaller and more numerous, there are still no “personalsatellites” and no mass producers of consumer products in the satelliteindustry today. It might be estimated that a network of microsatellitesin low Earth orbit and ground equipment to accommodate the tracking,transmission, reception, signal handoff among the plurality ofmicrosatellites and necessary system network for a voice system wouldcost at least $3 billion to deploy. Within four years of deploying asystem, each one of five million subscribers might be expected to investas much as $3,000 in the equipment, which results in a total combinedinvestment by the users in the new equipment of about $15 billion. Thecost of deploying a smaller system of low Earth orbit advanced messagingsatellites might be estimated at about $475 million. Such a system mightbe expected to serve two to three million subscribers, each with userequipment costing $300-$1,000. Thus, the total investments by the usersfor their equipment may be at least $600 million.

There is currently an industry involving radiosondes for purposes ofgathering weather information. Radiosondes are the instrument packageslaunched on weather balloons to gather weather data. Radiosondes arelaunched from a network of sites around the world at noon and atmidnight Greenwich Mean Time each day. The weather service radiosondescollect temperature, humidity, pressure and wind data as they rise fromthe surface of the Earth to approximately 100,000 feet during a two-hourflight. This data is then input in atmospheric models that are run onsupercomputers. The information gathered from the network of ascendingradiosondes is critical in predicting the weather. Most countries of theworld are bound by treaty to launch radiosondes from designated sitesand to share the data with other countries. Currently there are about800,000 radiosondes launched each year throughout the world. This numberrepresents the 997 global weather stations launching two radiosondes perday, 365 days per year (727,000) plus a small number of radiosondeslaunched for research purposes. About 18% of radiosondes are recovered,reconditioned and reclaimed, resulting in new production of about650,000 weather-gathering radiosondes per year.

The location systems currently used to track weather balloons are eitherbeing deactivated (Omega, beginning before the year 2000, and Loran-C,shortly after the year 2000) or are so old that the operation andmaintenance is becoming prohibitively expensive (radars andradiotheodolites).

Changes in radiosonde systems are usually very slow, sincemeteorologists study climatic trends by comparing data collected overdecades. Thus, they are very leery of any changes that may introduce newbiases into data as it is collected. This is evident from the fact thatmajor users, like the U.S. National Weather Services (NWS) still useanalogue radiosondes tracked by radiotheodolites when digital, navaidsondes have been around for many years. Tightening of governmentalbudgets has made some users unable to pay for new technology required.There presently is a push in the sonde marketplace to convert to usingthe Global Positioning System (GPS) for wind tracking on radiosondes.From 1995 to 1998, the NWS tried and failed to get the U.S. Congress tofund a program to develop a GPS tracking system for the U.S. ObservationNetwork. This inability to obtain the necessary newer technology toreplace old and unsupportable radiosonde infrastructure is occurringsimultaneously with the rapid reallocation of the radiosonde's RFspectrum to commercial uses. Radiosondes have traditionally transmittedat 400 MHZ for navaid sondes and 1680 MHZ for radiotheodolite sondes.The 400 MHZ band is being auctioned off by the Federal CommunicationsCommission (FCC) in the United States for simultaneous use by commercialservices. Thus, interference is increasing and sondes may be forced touse to narrower bandwidths with digital downlinks instead of the widebands with analogue downlinks still in common use.

Very large and expensive NASA balloons have been individually launchedand maintained at a floating altitude for extended periods of time.These balloons carry hundreds of pounds of equipment and cost tens ofthousands of dollars each. The single balloons do not have thecapability of line-of-sight coverage with entire geographic areas.

Personal communications services (PCS) are a new category of digitalservices that the FCC started auctioning spectrum for in 1994. PCS issplit into two categories: broadband and narrow band PCS. The broadbandcategory is primarily for voices services and PCS broadband phones nowcompete with traditional cellular phones. The narrow band category isfor advanced messaging, which is essentially two-way paging. The pagingindustry sees advanced messaging as being the mobile extension of one'se-mail account, just as a cellular phone has been the mobile extensionof one's desktop phone. Nationwide narrow band PCS (NPCS) was the firstspectrum ever auctioned by the FCC. About 30 regional and nationwideNPCS licenses have been auctioned and sold to private commercialventures. The fact that the spectrum was auctioned is significant inthat there are fewer restrictions on the use of this spectrum than onthe use of traditional spectrum licensed from the FCC. Before auctions,the FCC granted spectrum on a piecemeal basis, and companies had toprove that they were using the airwaves for the “public good.” Usuallythere was very specific federal regulation on how the frequency could beused. Since companies paid for their PCS licenses, they essentiallyowned the spectrum. The FCC imposed only minimal regulations required toprevent systems from interfering with other carriers' and othercountries' systems. Additionally, the FCC and Industry Canada reachedwhat is known as a Terrestrial Radio Communication Agreement andArrangement in which Canada allocated the same frequencies for NPCS withthe same channel structure as the auctioned spectrum for the NPCS in theUnited States. This made cross-border NPCS possible and in 1996, atleast one paging system company was granted an NPCS license in Canada tooperate on the same frequencies as its U.S. licensee. Mexico also hasspecified the same channel spacing as used in the United States.

One of the goals of the FCC is to encourage providing radio frequency(RF) communications services to consumers in rural areas at anaffordable price. This market has been largely ignored by the largercommunications companies because of the diminishing return on investmentin providing wireless communications to sparsely populated areas. Thesewireless services include paging, advanced messaging, telemetry, voice,etc. Although both voice and messaging services are available to ruralareas using satellite systems, the costs are generally in the thousandsof dollars per unit and well out of reach of most consumers. In additionsatellite systems have problems providing services in urban areasbecause they lack the signal strength necessary for providing buildingpenetration.

SUMMARY OF THE INVENTION

This invention relates to a rise rate control system to control a riserate of a free-floating lighter than air platform comprising a ventactuator, an altitude sensor and a device that controls the ventactuator when the rise rate is greater than a predefined rise rate.Preferably, the altitude sensor determines both an altitude of thefree-floating platform and the rise rate, the device determines the riserate and the device is located on the free-floating platform. The systemcould further comprise a ballast container, a ballast and a ballastdischarge actuator that controls a discharge of the ballast from theballast container when the rise rate is less than a particular riserate.

Another embodiment is a method of controlling a rise rate of afree-floating lighter than air platform by a rise rate control systemcomprising a vent actuator, an altitude sensor and a device thatcontrols the vent actuator when the rise rate is greater than apredefined rise rate, the method comprising determining the rise rateand controlling the rise rate. Preferably, the controlling the rise ratecomprises venting the vent actuator by the device. Preferably, the riserate control system further comprises a ballast container, a ballast anda ballast discharge actuator that controls a discharge of the ballastfrom the ballast container when the rise rate is less than a particularrise rate and wherein the controlling the rise rate comprisesdischarging the ballast from the ballast container.

Another embodiment is a method for determining a location of a devicetransmitting wireless signals with a plurality of free-floating lighterthan air platforms comprising taking signal path delay measurements fromthe plurality of free-floating lighter than air platforms anddetermining the location of the device transmitting wireless signalsbased on the signal path delay measurements, wherein the plurality offree-floating lighter than air platforms have a speed relative to thesurface of the earth of less than 100 miles per hour and float at analtitude of 60,000-140,000 feet, wherein the method does not require aDoppler shift correction. Preferably, the signal path delay measurementsare performed by measuring the difference between a time of arrival of awireless signal of the device transmitting wireless signals and astandard time and the determining the location of the devicetransmitting wireless signals is based on the signal path delaymeasurements from at least three independent free-floating lighter thanair platforms. In one embodiment, device transmitting wireless signalsis located on (a) a free-floating lighter than air platform that haslanded on the earth or (b) a ground-based vehicle, and the device is atransmitter or a transceiver. In one variation, the determining thelocation of the device transmitting wireless signals based on the signalpath delay measurements comprises determining distances from the deviceto the plurality of free-floating lighter than air platforms, tracingout approximate circles on the earth based on the distances anddetermining a point of intersection of the circles, the point ofintersection being substantially the location of the device transmittingwireless signals. In one variation, the taking signal path delaymeasurements is taking only two signal path delay measurement while inanother variation the taking signal path delay measurements is done bysectored or directional antennas.

Another embodiment is a method for determining a location of a payloadcomprising a device transmitting wireless signals and a GPS unit, themethod comprising measuring a location of the device transmittingwireless signals by the GPS unit, checking for a shift in the locationof the device transmitting wireless signals and communicating thelocation of the payload to a free-floating lighter than air platform.Preferably, the payload has landed on the earth and the free-floatinglighter than air platform floats at an altitude of about 60,000-140,000feet, wherein the method does not require a Doppler shift correction.

Another embodiment is a system for locating and determining usage of aground-based vehicle comprising a housing attached to a hub of theground-based vehicle, the housing comprising a GPS unit, a devicetransmitting wireless signals and a power source. The housing couldfurther comprise a tire rotation sensor. The system could furthercomprise a free-floating lighter than air platform comprising a devicereceiving wireless signals that receives signals from the devicetransmitting wireless signals. Preferably, the power source is a solarpower source, a battery, a generator, or combinations thereof.

Another embodiment is a method for steering a steerable systemcomprising flying the steerable system in a circle relative to a localwind at the steerable system thereby nullifying a flight vector of thesteerable system and determining a local wind vector of the local windwith respect to a position on the earth without using data obtained froma compass or an air speed indicator. Preferably, the steerable system isan autonomous, GPS guided steerable system that does not have thecompass or the air speed indicator onboard the steerable system. Furtherpreferably, the determination of the local wind vector is based on aground track vector of the steerable system. Furthermore, the groundtrack vector could be obtained from a GPS unit located on the steerablesystem. Preferably, the steerable system is a component of afree-floating lighter than air platform floating at an altitude of about60,000-140,000 feet.

Another embodiment is a method for determining a location of a devicetransmitting wireless signals with one or more free-floating lighterthan air platforms comprising taking signal path delay measurements fromthe one or more free-floating lighter than air platforms at differentintervals of time and determining the location of the devicetransmitting wireless signals based on the signal path delaymeasurements, wherein the one or more free-floating lighter than airplatforms have a speed relative to the surface of the earth of less than100 miles per hour and floats at an altitude of 60,000-140,000 feet,wherein the method does not require a Doppler shift correction.Preferably, the one or more free-floating lighter than air platforms hasone free-floating lighter than air platform. Also, the one or morefree-floating lighter than air platforms could have two free-floatinglighter than air platforms.

Another embodiment is a system for locating and determining usage of aground-based vehicle comprising a housing, the housing comprising a GPSunit, a device transmitting wireless signals and a power source, thesystem further comprising one or more free-floating lighter than airplatforms comprising a device receiving wireless signals that receivessignals from the device transmitting wireless signals. Preferably, theone or more free-floating lighter than air platforms have a speedrelative to the surface of the earth of less than 100 miles per hour andfloats at an altitude of 60,000-140,000 feet, wherein the system doesnot require an instrument for a Doppler shift correction.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the invention may be had with reference to theattached drawing Figures in connection with the Detailed Descriptionbelow in which like numerals represent like elements and in which:

FIG. 1 schematically depicts a flow diagram of combined methods of atermination decision by a processor or controller including terminationcriteria, criteria detection by sensing of geographic position andvelocity and elements of operation according to certain aspects of theinvention;

FIG. 2 schematically depict a mechanism for the controlled release ofballast according to certain aspects of the present invention;

FIG. 3 is a schematic partial front view of a neck of a platformconnecting between a balloon and a payload with a line and depicting theconstruction and method of releasing a balloon from the payloadplatform.

FIG. 4 is a schematic partial front view of the neck of a platformconnecting between a balloon and a payload as in FIG. 3 furtherdepicting the release of the balloon from the payload platform;

FIG. 5 is a schematic diagram for a battery discharge and neck releasecircuit;

FIGS. 6, 7 and 8 are front side and end views, respectively, of a “mapleseed” descent mechanism attached to the bottom of a platform accordingto one embodiment of certain aspects of the invention;

FIG. 9 is a schematic depiction of a landed terminated platform (with orwithout a balloon) transmitting a locator signal to a floating platformtransceiver that relays the locator information to a ground station tofacilitate recovery of the terminated platform.

FIG. 10 is a schematic showing the hand-off mechanism; and

FIG. 11 is a schematic partial front view of a neck of a platformconnecting between a balloon and a payload with a pin and depicting theconstruction and method of releasing a balloon from the payloadplatform.

FIG. 12 is a schematic depiction of a plurality of airborne platformsrepresenting a constellation of platforms over a contiguous geographicarea, launch facilities and communication terminals, networked togetherwith a network operations center through ground lines and,alternatively, through orbiting satellite communication signals.

FIG. 13 is an enlarged depiction of a plurality of airborne platforms, asingle moveable launch site and communication terminal with networklinkage to a network operation center for a plurality of groundterminals and personal communication devices;

FIG. 14 is a schematic depiction of inter-platform communications withsubsequent transmission to ground terminals and to a network operationcenter (NOC).

FIG. 15 is a schematic depiction of platform-to-space satellitecommunication links for providing the network interconnection with anetwork operation center (NOC).

FIG. 16 is a schematic depiction of “hub and spoke” networkcommunication link topography.

FIG. 17 is a schematic depiction of mesh network communication linktopography.

FIG. 18 is a schematic depiction of a contiguous geographic area,particularly the United States, with airborne SNS platform launch sitesand showing initial coverage area SAS circles, superimposed on a map ofthe geographical area and demonstrating the line-of-site coverage areasfor each SNS platform such that substantially the entire geographic areais encompassed within the reception range of one or more of the airborneplatforms.

FIG. 19 is a schematic depiction of an example of airborne platformmigration after a period of regulated altitude free-floating of theairborne platforms and also depicting additional gap-filling launchsites, that may be provided by mobile launchers, to supplement andcomplete the continuity of coverage with additionally launched airbornecommunication platforms.

FIG. 20 is a schematic side view of an airborne platform in which alighter-than-air gas enclosure, such as a balloon, is attached to a boxholding the electronic controls, communications devices, sensors and ameteorological data-gathering package.

FIG. 21 is an enlarged partial cross-section of an airborne platform,including the control and communications box fastened to alighter-than-air gas enclosure, or balloon, according to one embodimentof the present invention.

FIG. 22 is a side partial cross-sectional view of the airborne controland communications platform of FIG. 17 according to one embodiment ofthe invention.

FIG. 23 is a partial cross-sectional side view of an alternativeembodiment of a control and communication platform in which an alternatepower source, including a hydrogen/oxygen-powered fuel cell is used inplace of the batteries of the embodiment of FIG. 18.

FIG. 24 is a schematic block diagram of an electronic circuit forcontrol, sensing, and communications according to one embodiment of theinvention.

FIG. 25 shows a lighter-than-air platform in two-way communication witha ground-based transceiver.

FIG. 26 shows a ring of equal propagation delay from a lighter-than-airplatform on the ground.

FIG. 27 shows rings of equal propagation delay from two separatelighter-than-air platforms.

FIG. 28 shows a weatherproof housing for attachment to the hub of a semitrailer wheel for the purpose of measuring the semi trailer usage andlocation.

FIG. 29 shows a ground track vector.

FIG. 30 shows a ground track vector and flight vector.

FIG. 31 shows a ground track vector, flight vector and calculated windvector.

FIG. 32 shows the full circle procedure under no wind for effectivelynullifying the flight vector.

FIG. 33 shows the full circle procedure under wind for effectivelynullifying the flight vector.

DETAILED DESCRIPTION OF THE INVENTION

The present invention overcomes drawbacks of prior communicationsatellites, by using small and relatively inexpensive microelectronicsto incorporate most of the functions provided by existing communicationsatellites in small, lighter-than-air communications platforms. Inparticular, a plurality of lighter-than-air balloons is designed tocarry microelectronic communication equipment into a layer of theEarth's atmosphere called the stratosphere. The weight of theseplatforms is approximately 100 to 1,000 times less than themicro-satellites currently launched into non-geosynchronous orbits. Forconvenient reference, the airborne communication platforms or balloonscarrying a payload of electronic communication and control equipmenthave sometimes been referred to herein as “stratospheric nanosatellites”or “SNS” for short. In the metric system, the “nano” prefix signifiesunits 1,000 times smaller than the “micro” prefix. The SNS inventioneliminates the need for a rocket to propel the satellite into orbit.Synchronized airborne launching of a plurality of the SNS platform atspaced-apart geographical locations provides a low cost constellation ofsatellites. The SNS platforms rise after launch to a controlled,adjustable altitude where they migrate over the geographic areaaccording to ascent atmospheric and the stratospheric weather conditionsand particularly the winds. The SNS platforms may be raised or loweredin altitude by gas venting or ballast drop in order to catch prevailingwinds favorable to keep the SNS platforms evenly spaced apart. Theplatforms are caused to rapidly descend when no longer needed.

Existing user equipment designed for terrestrial wireless communicationcan work with the SNS system of the present invention. This is not thecase in the traditional communication satellite industry, since eitherthe communications satellites are very far from the user (more than22,000 miles for geosynchronous satellites) making the signal too weakwithout specialized user equipment, or the satellites travel at highspeeds relative to the users on the ground (more than about 36,000 mphfor low earth orbit satellites) causing phase errors in the receiver.The SNS platform is, at most, about 175 miles (280 kilometers) from theground user, depending upon the altitude and the radial coverage rangefrom the particular platform among the plurality of platforms coveringthe geographic area. Moreover, the airborne platforms move at speedsapproximating the speed of an automobile (between about zero and 60 mphat their float altitude). Compatibility with existing wirelesscommunication systems is a significant advantage because when deployinga new communications system, the user equipment investment is always thelargest total investment required.

In contrast to the large deployment and new equipment costs for orbitingsatellite systems, the present invention provides a low cost alternativethat does not require new subscriber equipment. Thus, a benefit of theSNS System is an advanced messaging SNS network that is compatible withstandard one-way and two-way pagers already in existence and already inuse with tower-based transceiver networks. Even without consideringdeploying of the SNS system, market analysts predict 35 million userswill be carrying compatible, standard two-way pager equipment by theyear 2003. At, for example, $100/unit, this represents an investment byusers of over $3.5 billion. These users can receive the enhancedcoverage of the inventive SNS platform network as an extension of theirpresent service simply by electing to pay the monthly and incrementalusage fees. There are no up-front costs for new user equipment ortraining and no need to change the user's habits and burden them withcarrying more than one pager or other communication device as is thecase with current satellite pagers.

Furthermore, the inventive SNS system, when performing advancedmessaging, uses a communication or pager protocol that is being adoptedinternationally. International opportunities for the new system are atleast equal to the U.S. potential. The SNS System may utilize otherpopular paging protocols as well. The system also has uses beyondpersonal paging for other communications, remote, imaging, infraredscanning, equipment tracking and weather data collection services.

It will also be beneficial for the National Weather Service (NWS) toconsider utilizing the current SNS invention as a replacement systemcapable of providing the NWS with required information during the ascentof SNS platforms. GPS information available from the SNS Platform couldprovide the desired wind information the NWS needs but is unable toafford. Existing NWS launching facilities might even be used as SNSlaunch, tracking and communication sites. After the ascent andtransmission of weather data to the NWS, the platform would then becontrolled to float at a regulated altitude and to provide othercommercial communications services. The NWS sondes could be removablyattached and dropped as ballast after the ascent is complete and thedesired information there from has been transmitted to the NWS. Theattached radiosondes could use exactly the same sensors utilized in thecurrent radiosondes in order to keep the data consistent with currentradiosonde data.

The inventive SNS network is uniquely designed to cover large areas andto use dedicated frequencies on a national, and ideally, on aninternational basis, between bordering countries. It is beneficial toallocate nationwide, or ideally international dedicated frequencies tothe SNS system due to the large coverage circles of each of the SNSairborne platforms. Overlapping use of the same frequency without timemultiplexing the signals would most likely cause interference at thereceiver. The System will optimally work within a range of frequenciesdesignated the “Narrowband Personal Communications Services” or “NPCS”spectrum. Moreover, the entire NPCS industry in the U.S. has generallyagreed on a standard two-way messaging protocol called “REFLEX”. REFLEXis a protocol that uses time division multiple access (TDMA). The REFLEXprotocol is an extension of the FLEX protocol designed by Motorola andis a synchronous protocol where there are 128 frames in a four-minutecycle. The start and end of each frame is coordinated nationwide usingGPS technology for timing. This will allow a single frequency to beshared between the SNS network of the present invention and existingterrestrial satellite networks by simply allocating a certain number offrames to each network during each four-minute cycle. Thus, thedisclosed SNS system can either operate on its own dedicated frequenciesor interoperate with terrestrial systems on the same channel and nevertransmit on top of each other. This is unique to REFLEX and ispreferably incorporated into the new SNS system. The SNS may also workusing other protocols that utilize code division multiple access (CDMA)as well.

In contrast to most voice and paging networks where many differentprotocols are used over a wide range of frequencies, NPCS contains anear contiguous set of nationwide frequencies in which nationwidenarrowband PCS licensees have adopted the FLEX/REFLEX protocol.

The present inventive SNS system benefits from a nationwide consistencyof frequencies and protocols so that it can relatively easily operateacross all NPCS channels owned by any or all of the nationwide carriersif need be. Minimal governmental regulation of the NPCS bands also allowthe new SNS system, which was unknown when the NPCS regulations weredrafted, to operate in the NPCS bands without violating currentregulations. Since the NPCS licensees essentially own the frequenciespurchased at auction, and the inventive SNS system can compatibly usethe same frequencies with permission from the purchaser, additionallicenses from the FCC may not be needed. This unique feature also savestwo or three years in start-up time that it can sometimes take in orderto pursue separate licenses.

As discussed briefly above, in addition to minimizing the regulatoryhurdles, the new SNS network has a huge advantage in that it does notrequire new, specialized user equipment. It is expected that there maybe as many as between 6-15 million units of compatible user equipmentoperating off existing terrestrial satellite networks. These can simplybe added to the new SNS system using inexpensive system programming andthereby receive the expanded, more complete, coverage of the contiguousgeographic area provided by the constellation of floating communicationplatforms according to the present invention. To the NPCS carrier, thenew system can provide complete communication coverage, particularlycoverage in remote non-metropolitan.

Since existing paging equipment owners and users may acquire theexpanded coverage provided by the present invention through theirexisting carrier, the decision to expand coverage can be as simple aschecking a box on their monthly bill. They could keep their current pagesystem company, and simply add the benefit of remote area coverageprovided by the SNS. No new equipment is needed and no start-up time isneeded to learn the features of a new electronic gadget. There is simplyimproved coverage for the user without changing equipment. A veryimportant benefit of the inventive SNS network is the significantimprovement in complete remote area geographic coverage. Currently,wireless data coverage is a patchwork of covered high-density populationareas, primarily around metropolitan areas. The SNS network workscooperatively with the existing coverage areas and fills in all thelow-density population and thus low communication traffic areas allusing the same subscriber device. The governmental regulations governingNPCS systems require minimum system build-outs for all licensees. Forexample, by about 1999, a licensee providing NPCS must service at least37.5% of the U.S. population or 750,000 square kilometers, and by theyear 2004, a NPCS licensee must service at least 75% of the U.S.population, or 150,000 square kilometers. Since the population is veryconcentrated, prior systems have been required to build towers forcoverage over a very small percentage of the total landmass. In fact,the minimum area requirement for the 1999 and for the 2004 populationservice limits correspond to approximately 8% and 16% of the total U.S.landmass, respectively. Because of the high population density in U.S.cities. For example, covering 90% of the population requires a carrierto build out only about 20% area coverage of the country's totallandmass. Servicing areas of low population density is more expensivefor prior systems since tower transmitter/transceivers have a shortrange so that much more equipment is needed per potential customer.Thus, few prior carriers have systems that cover more than 90% of thepopulation because of the diminishing returns. Many established wirelessdata carriers are built out only to about 70%-80%.

The present invention is designed to provide substantially 100% coverageand can be compatibly combined with existing high density wirelesscarrier systems and networks such that the high density build-out byprior paging system carriers handles the high population densitygeographic areas and the low population density or remote area, whereverthey might be located within the contiguous geographic area, are pickedup and handled by the inventive SNS system. The SNS system iscomplementary to high-density tower paging systems. Thus, although theSNS system has a lower total signal handling capacity when compared tohigh population density tower systems, it provides complete geographiccoverage so that subscribers in or traveling through remote areas areprovided with the additional coverage of the SNS system. Subscribers arealways within the range of paging services or other compatiblecommunication services using a single device. The SNS system may alsoreallocate capacity on a regional basis by launching more SNS platformsor by reallocating the frequency use dynamically among the neighboringplatforms.

The SNS system also has uses beyond personal paging for othercommunications, voice, remote imaging, infrared scanning, equipmenttracking and weather data collection services. Broadband PCS (BPCS)phones that have come to market in the past year all offer an advancedmessaging service call Short Messaging Service (SMS). The SNS systemcould page a subscriber's phone when the phone was out of the BPCS phoneservice area. BPCS voice service may also be possible with an SNSsystem. Another potential application for SNS technology is the remoteimaging market. Governments, city planners, farmers, environmentalists,mapmakers, and real estate developers all rely on aerial or satellitephotos. Worldwide, this market is over $1.4 billion. Since an SNS isover twenty times closer to the subject than a satellite, SNS canachieve one-meter resolution with only a 0.75-inch diameter lens.Weather data from the extended stay in the stratosphere can be collectedand reported by the SNS platform as current radiosondes do not have thecapability of maintaining a float altitude.

An embodiment of the present invention is a constellation of smallairborne communications platforms with a ground network of launching,tracking and communication terminals. Although the entire system isdescribed primarily in terms of communications that are in the form of apaging system, other communications such as voice communications,emergency road service, search and rescue, emergency medical, remoteimaging, environmental monitoring, industrial & utility monitoring,remote asset management, photo data, IR scanning, equipment tracking,boxcar and container tracking, vehicle security, personal security,hazardous materials, customs and international shipping security, childsecurity, wildlife tracking, personal messaging, communications for thehandicapped, SCADA, trucking communications and shipment tracking, andmany other adapted communications might be easily included. As it isused here, paging includes traditional one-way paging as well as neweradvanced messaging services (such as two-way paging and voicemessaging). The airborne constellation of communications platforms andground support system extends the limited coverage of current pagingnetworks to provide complete communications coverage over an entirecontiguous geographic area. For example, in the U.S., it provides true,nationwide coverage. The ground based tower systems already in placeprovide the in-building coverage needed in the urban areas while the SNSSystem provides coverage of the low population density, rural areas.Thus a subscriber can have complete nationwide coverage using the samehandheld paging device. The inventive system does this by providing aconstellation of evenly-spaced, high altitude, airborne communicationplatforms, for example, balloon-carried paging transceivers, as opposedto the traditional systems of ground-based communication towers coveringonly a limited area or, as opposed to very expensive orbiting, high orlow altitude, satellite communications systems.

To form the constellation of airborne communications platforms, pagingtransceivers are attached to lighter-than-air carriers, such as highaltitude balloons similar to those used by the National Weather Service(NWS) yet modified to provide for regulated adjustable altitude controlusing methods such as gas venting and ballast dropping. Thelighter-than-air carrier or balloon and the attached communicationsdevices have been referred to in this application as stratosphericnanosatellite platforms (SNS platforms). For coverage of a contiguousgeographic area consisting of the Continental United States, SNSplatforms may be launched periodically at regular intervals or as neededfrom approximately 50 to 100 sites throughout the United States. Theselaunch sites may be selected for launching the balloon-carriedtransceiver to rise to a regulated floating stratospheric altitude ofapproximately 60,000 to 140,000 feet. Computer regulated altitudecontrol and computerized tracking are utilized. The SNS platforms areregulated to maintain a desired altitude within a predetermined altituderange, as, for example, in the stratosphere over the Earth, as theydrift along with existing wind currents. New SNS platforms may belaunched to fill any gaps that may occur in the coverage as theplatforms drift at different speeds, as they lose buoyancy or as theyoccasionally burst or malfunction. New SNS platforms may also belaunched to provide additional communications capacity as the needarises. Newly launched SNS platforms can collect, record and transmitmeteorological data during the ascent to the regulated altitude. Suchdata might be beneficially communicated via radio to the ground for useby the National Weather Service (NWS). The process of modeling andthereby predicting the coverage of the network of SNS platforms on acontinuous basis is a complex task due to the constantly changingweather conditions. This task is facilitated by also using the weatherdata recorded and/or transmitted to the ground for predicting themovement of individual platforms relative to each other and relative toground launching and tracking terminals. This data may also be used tocontrol the altitude of individual SNS to catch favorable prevailingwinds to help fill gaps in coverage. Each floating satellite at astratospheric altitude will have line-of-sight radio communicationcoverage at a radius of approximately 175 miles (280 km) in alldirections from antenna suspended below and forming a part of thecommunications platform.

Ground based support for the plurality of SNS platforms forming theconstellation comprises at least one network operations center (NOC) anda plurality of launching and tracking terminals. The NOC is preferably ahigh speed, high volume, computing, communications and operations centerfor the SNS system. The NOC may be in charge of all controllable aspectsof every communications platform's flight and operation. These controlsinclude platform launches, floating altitudes, tracking, all pagingcommunications and control signal transmissions, and communications withpartnering paging companies. Typically, the SNS ground terminals includelaunch facilities, tracking and communications equipment andcommunication antennas. The co-located launch facilities and groundterminals may also advantageously correspond with existing locations ofthe approximately seventy NWS balloon launch facilities that aredesigned to monitor weather conditions nationwide. Similar Weatherstations also exist and are maintained by treaties essentiallyworldwide. These ground terminals may be automated. Portable or mobilelaunching and tracking ground terminals can also be used when necessaryto fill in anticipated coverage gaps that may develop between theoverlapping circular coverage patterns of the floating platforms. Theseportable or mobile launching and tracking ground terminals may be movedseasonally to provide additional launch sites as the stratospheric windschange on a seasonal basis. These would most likely be positioned alongthe coastline or the edges of the coverage area. The ground terminalscan advantageously track a number of SNS platforms floating near theirlocation and can provide the uplink and downlink of all communications,including paging and control data, to each platform within range of theterminal. Paging signals from a subscribing paging company may be sentto the SNS system through the NOC. The NOC determines which SNS platformis currently over the addressed pager and sends the paging message tothe ground terminal that is tracking that SNS platform. The groundterminal receives the paging message from the NOC and relays it to theSNS platform. The SNS platform then transmits the paging message down tothe individual pager. Any message sent by a two-way pager is received bythe nearest SNS platform and relayed down to the ground terminal. Theground terminal sends the message to the NOC, which relays the messageto the appropriate subscribing paging carrier. The NOC also keeps trackof all billing information and subscriber location information. The SNSsystem is advantageously designed to be fully compatible with FLEX(one-way pagers) and also REFLEX (two-way pagers) without modificationto the pagers. The launch facilities, whether co-located with NWS launchfacilities or separately located at other selected ground locations, mayconsist of a fully automated launcher and ground terminal. One groundterminal may control multiple SNS platforms at one time. Land lines,satellite links or other high signal capacity network communicationscoupling from one ground location to another may be used to connect theplurality of launch sites and ground terminals to each other or the NOC.

One embodiment of this invention is a system comprising a free-floatingplatform and a communication device that is separate from the platform,the platform comprising a lighter-than-air gas enclosure and a payload,the payload comprising a processor and a transceiver, wherein theprocessor is capable of making a decision to terminate a flight of theplatform, the transceiver is capable of receiving a signal from thecommunication device, and the communication device is capable of handingoff the signal to another transceiver of another free-floating platform.The payload could further comprise an altitude sensor, a position sensorand a power source. Typically, the payload is within 500 feet of thelighter-than-air gas enclosure.

The decision is based at least in part on (a) if the platform isdetermined to be outside specified geographic boundaries; (b) if theplatform is outside of a specified altitude range; (c) if the platformhas a lateral or vertical velocity outside a specified range; (d) if theprocessor fails; (e) if a power source fails (f) if a command andcontrol communications link fails.

The decision could be releasing of a ballast, stopping a signal to adischarge circuit to prevent a battery from discharging, releasing theplatform from the payload, or combination thereof.

Another embodiment of this invention is a method of terminating a flightof a free floating platform, wherein the platform comprises atransceiver capable of receiving a signal from a communication devicethat is separate from the platform, the method comprising determining ageographic position and/or a velocity of the platform, making a decisionwith a processor on the platform to terminate the flight of theplatform, handing off the signal to another transceiver of anotherfree-floating platform and terminating the flight of the platform.

Yet another embodiment is a system for ascending or slowing the descentof a free floating platform, comprising a lighter-than-air gas enclosureand a ballast comprising reactants that form a gas that is lighter thanair when the reactants are mixed. The gas could be hydrogen and thereactants could comprise water and a hydride of Ca or Na. At least oneof the reactants should be heavier than air. For example, at least oneof the reactants could be a hydrocarbon. The system could furthercomprise a catalyst for reforming at least one of the reactants.

Another embodiment of this invention is a method for ascending orslowing descent of a free floating platform, the method comprisingreacting reactants stored on the platform to form spent reactants and agas that is lighter than air, introducing the gas into alighter-than-air gas enclosure and dropping the spent reactants.

Another embodiment of this invention is a system for terminating aflight of a free floating platform, comprising a lighter-than-air gasenclosure, a payload and an element, wherein the element is capable ofseparating the gas enclosure from the payload. The element couldcomprise a line and a component capable of breaking the line. The systemcould further comprise two axially aligned tubes connecting the payloadto the gas enclosure. In a preferred embodiment, the element could be apin.

Yet another embodiment of this invention is a method for terminating aflight of a free floating platform comprising a lighter-than-air gasenclosure, a payload and an element, wherein the method comprisesseparating the lighter-than-air gas enclosure from the payload by anaction of the element. The method could further comprise passing currentthrough the element.

Another embodiment of this invention is a power system comprising abattery, a processor and a discharge circuit, wherein the processorintermittently sends a signal to the discharge circuit to prevent thebattery from discharging. Preferably, the processor stops sending thesignal when the power system lands on ground or water.

Yet another embodiment of this invention is a method of recovering afree floating platform, comprising landing the platform on ground orwater and sending a position of the platform to a transceiver located onanother free floating platform. The method could further comprisetransmitting the position from the transceiver located on anotherfree-floating platform to a transceiver located in a ground station.

Another embodiment of this invention is a system for terminating aflight of a free-floating platform, comprising a lighter than air gasenclosure, a payload and means for releasing the gas enclosure from thepayload. The means for releasing the gas enclosure of those disclosed inthe specification and equivalents thereof.

It has been found that the previous largest use of unmannedlighter-than-air ballooncraft has been by the various weather servicesof the world. For weather data acquisition purposes small latex weatherballoons carry instrument packages called radiosondes to gather weatherdata. These weather balloons are launched from a network of sites aroundthe world at noon and midnight Greenwich Mean Time each day. The weatherservice radiosondes collect temperature, humidity, pressure and winddata as they rise from the surface of the Earth to approximately 100,000feet during a two-hour ascent. At approximately 100,000 feet the weatherballoons burst and the radiosonde payload falls to earth on a parachute.This data acquire during the ascent is input into atmospheric models runon supercomputers to facilitate predicting the weather. The input datais limited as it represents only a snapshot of the weather data takenduring the balloon ascent every 12 hours. The ascent and decent arerapid, mostly landing within the originating country's borders such thatthe short duration radio transmissions and physically crossing bordersare not major issues. Also, most countries of the world are bound bytreaty to launch balloon carried radiosondes from designated sites andto share the data with other countries.

Currently there are about 800,000 radiosondes launched each yearthroughout the world. There are also a small number of research balloonslaunched for research purposes. The research balloon may be quite largeand flights typically are done using special frequencies and withinternational or individual country permission for border crossing. Thetotal number of balloon flights per year primarily comprises the 997global weather stations launching two radiosondes per day, 365 days peryear (727,000). Only about 18% of these radiosondes are recovered,reconditioned and reclaimed, resulting in the new production of about650,000 weather-gathering radiosondes per year.

The Federal Communications Commission (FCC) prohibits uncontrolledtransmitters as they may cause interference to users on the samefrequency or others on nearby frequencies. FCC spectrum licensesgenerally prohibit a US licensed transmitter from transmitting when itleaves the border of the US.

It has been found that most lighter-than-air platforms that maintainaltitude must drop ballast in order to maintain altitude as lifting gasis lost through the balloon membrane and as the heating effect of thesun is lost as night approaches. The Federal Aviation Administration(FAA) regulations Section 101.7 states that unmanned ballooncraft areprohibited from dropping objects or operation such that a hazard mayoccur. Sec. 101.7 Hazardous operations.

(a) No person may operate any moored balloon, kite, unmanned rocket, orunmanned free balloon in a manner that creates a hazard to otherpersons, or their property.

(b) No person operating any moored balloon, kite, unmanned rocket, orunmanned free balloon may allow an object to be dropped there from, ifsuch action creates a hazard to other persons or their property.

-   (Sec. 6(c), Department of Transportation Act (49 U.S.C. 1655(c)))-   [Doc. No. 12800, Arndt. 101-4, 39 FR 22252, Jun. 21, 1974]

A major factor influencing the size and cost of a lighter-than-airplatform is the weight of the payload. For small ballooncraft such asweather balloons, they may become exempt from certain FAA reporting,lighting, and launching requirements if the total payload weight is keptbelow 6 pounds and a density of 3 ounces or less per square inch of thesmallest side.

-   Sec. 101.1 (4) Applicability.

This part prescribes rules governing the operation in the United States,of the following:

(4) Except as provided for in Sec. 101.7, any unmanned free balloon that

(i) Carries a payload package that weighs more than four pounds and hasa weight/size ratio of more than three ounces per square inch on anysurface of the package, determined by dividing the total weight inounces of the payload package by the area in square inches of itssmallest surface;

(ii) Carries a payload package that weighs more than six pounds;

-   -   [Doc. No. 1580,28 FR 6721, Jun. 29, 1963, as amended by Arndt.        101-1, 29 FR 46, Jan. 3, 1964; Arndt. 101-3, 35 FR 8213, May 26,        1970]

The unique use of a light, and low-density payload also significantlyreduces costs associated with the launch and allows a launch to occur inall weather conditions. The amount of ballast required to keep aplatform within a set altitude range over a 24-hour period is typicallyon the order of 15% of the total system weight. This is a significantpercentage of the total weight for a floating platform especially forballooncraft missions that may last multiple days. For example, it hasbeen found that a three day flight may require that 38% of theplatform's system weight be ballast. This results in eithersignificantly increasing the size of the balloon or decreases the weightavailable for the payload.

The two sections of the FAA regulations above show the FAA's concernwith increased payload weights and densities. This concern appears tofocus on reducing the potential for damage to an aircraft in acollision. The density and total weight of the payload are also found tobe significant factors in overall safety upon the payload's return tothe earth. Generally lower weight and density payloads, are believed toreduce the chances of causing physical damage, and as a beneficialresult may also be easier and less costly to insure as well.

The FAA further prohibits uncontrolled lighter-than-air free driftingballoons. Again there may be a concern that uncontrolled flight maypresent a hazard to aircraft. For example, in 1998, the Canadian SpaceAgency lost control of a large scientific balloon. This promptedre-routing of trans-Atlantic passenger flights for 10 days as theballoon drifted from its launch site in Canada until it finally landedin Finland. The uncontrolled balloon also resulted in aviation concernsin Russia and Norway. Significant resources were expended, including theuse of fighter jets to try to bring the uncontrolled balloon down.

Until now, unmanned, free drifting, lighter-than-air balloons have beeneither restricted to short flights as is the case with the 50,000 NWSweather balloons launched each year, or a very few large and expensivelong duration scientific flights. The NWS weather balloons have anextremely limited life (approximately 2 hours) and their transmittersand batteries have limited power. The long duration scientific balloonstypically have long lives and extended missions. These infrequentballooncraft flights are expensive and generally require frequency andsafety coordination with each country that they overfly. They may gainauthorization to use government or scientific frequencies for shortperiods of time that are not available for commercial users.

Applicants, as disclosed in a co-pending application, have discoveredand developed new and commercially viable uses for small free-floatingplatforms with long duration capabilities. These small, long durationballooncraft or free floating platforms have long flight lives similarto much larger scientific ballooncraft and the ability to travel longdistances. The present methods and inventive devices also facilitatereducing the massive reporting and coordination requirements of thelarger ballooncraft. The free-floating platforms may be operating oncommercial frequencies that have specific laws as to the use of thefrequencies in each country. The innovative new methods facilitatemaintenance of legal transmitter operations, particularly at borders,they provide for platform flight termination for rogue, uncontrolled ormalfunctioning platforms, they provide for environmentally acceptabledescent and they enhance the opportunity for recovery and reuse of thesedevices. All of these methods are especially useful as they relate toregional and international borders. The present invention uses specificcriteria and elements of operation or sets of criteria and elements ofoperation that taken as a whole form a safe method for reducing orpreventing illegal transmissions, for terminating flight, for rapidlydescending the platform to the ground, for environmentally acceptablelanding and for enhanced recovery. All the methods are designed toenhance safety and to comply with known regulations.

FIG. 1 schematically depicts a flow diagram of combined methods of atermination decision by a processor including termination criteria,criteria detection by sensing of geographic position and velocity, andelements of operation according to certain aspects of the invention. Incombination with an onboard power source 12 and GPS 14 (or othergeographic locator or tracking system), a processor 10 is provided toreceive position information and time change of position (velocity)information 14. The position information is compared to stored orprogrammed criteria information at 16, 18, 20, 22, 24, 26, 28 and 30, todetermine whether termination of radio transmission and/or terminationof flight should be implemented.

The following criteria based decisions are provided with the processor10:

Has the Platform Moved or Drifted Outside of a Certain Geographic Area?(See FIG. 1, at 16.)

The relevant boundaries may be frequency license borders set by the FCCas dictated by a regional or nationwide broadcasting license. The FCCprohibits transmitter operation outside such geographic borders.Additionally, a neighboring country may have restrictions on transmittedpower into their country from a foreign transmitter. It has been foundthat on certain frequencies Mexico prohibits transmit power levels above−99 dBm into Mexico from the United States. These restrictions are nothard for terrestrial towers to comply with as the towers can install andadjust directional antennas once during installation and not have toadjust them again thereafter. This is quite different for a freedrifting high altitude ballooncraft containing a transmitter as theposition and altitude may be constantly changing and may require theplatform to stop transmitting while still inside the United States, butwithin a protective number of miles of the United States-Mexico border.Long duration scientific ballooncraft are not as concerned with this asthey typically work on special frequencies or have coordinated withother countries that may be over flown.

Is the Platform Moving Outside of Boundaries that would SignificantlyReduce the Probability of Recovering the Platform? (See FIG. 1 at 18.)

As payloads costs may be significant, from $50 to $150 for a typicalweather service radiosonde, up to hundreds of dollars for a transceiverplatform, and up to many tens of thousands of dollars for a scientificpayload, recovery is important both financially and for environmentalreasons. A platform may encounter strong winds especially in the jetstream as it descends from high altitudes. In order to keep the platformfrom drifting out of the country on descent, artificial borders thattake into account the winds during descent can be used. Also, boundariesof large bodies of water such as the great lakes, seas and oceans thecrossing of which might hamper or prevent recovery of the platform uponnormal decent, may be taken into account for termination of flightpurposes.

Has the Platform Fallen Below or Risen Above a Set Altitude Range? (SeeFIG. 1 at 20)

Most scientific and weather balloons reach altitudes above 60,000 feet,The FAA regulates airspace below 60,000 feet and discourages freefloating craft or uncontrolled flight craft from loitering especially incommercial air lanes as they present a hazard to commercial planes.Current NWS weather balloons do not have the capability to terminate theflight if they start to hover below 60,000 feet. Even the large-scalescientific balloons may become errant and free drift below 60,000 feet.(see the rogue scientific balloon example listed earlier).

Is the Platform Velocity Sufficient to Create an Unacceptably LargeDoppler Shift in the Transmission Frequency? (See FIG. 1, at 22)

A ballooncraft traveling in the jet stream may reach speeds of over 180miles per hour. This creates a Doppler shift in the frequencies receivedon the ground. The FCC regulates the amount of total frequency driftallowed on transmissions. Doppler shift contributes to this totalfrequency drift and if great enough can cause the transmitter totransmit out of its allowed band. These requirements have not beenconsidered or accounted for in the past as free drifting commerciallytransmitting platforms were not available. Therefore, the requirementthat the payload be able to immediately stop transmitting past the speedat which the Doppler becomes too great is new.

Does the Platform Fall Rate Indicate a Balloon Burst? (See FIG. 1, at24.)

A fast fall rate indicates that the balloon has burst and that the craftis falling.

Is the Lighter-than-Air Platform Rising too Slowly during Ascent? (SeeFIG. 1, at 26.)

This indicates that the balloon is under-filled or leaking A slow riserate may present a danger to aircraft by loitering excessively at onealtitude particularly at an altitude in designated air lanes.

Has the Processor, the Position Finding Equipment, or the Primary PowerFailed? (See FIG. 1, at 28.)

A GPS, star tracker, or system power failure should initiate an on-boardtermination. The platform must be able to terminate without processorcontrol or power.

Have Command and Control Communications been Lost? (See FIG. 1, at 30.)

Without command and control from the ground, the payload should ceasetransmission and the flight should be terminated.

The present inventive system detects the foregoing conditions bycomparing current position, velocity, and operating conditions tostored, programmed or calculated criteria using an onboard processor orcontroller. The present invention utilizes a GPS unit and a processor todetermine the current platform's geographic coordinates and velocities.A GPS unit or pressure sensor determines the platform altitude. Theprocessor algorithms will implement the complete set of conditionslisted above causing the ballast to be released at 34, the transmitterto be shut off at 38 and the flight terminated at 36 upon detection of astored, programmed or calculated termination criteria. Under conditionsof a power loss or processor failure, the transmitter will also be shutoff at 38, and the flight will be terminated at 36. The methods andmechanisms for the termination actions are described more fully below.

A separate termination controller 11, which may be under separate power13 monitors the primary platform power at 32 and monitors processorfunctions at 30 to determine if the processor 10 is functioningproperly. Both the primary processor 10 and the separate terminationcontroller 11 have the ability to terminate transmissions, bydischarging the primary platform batteries at 38 and to terminate theflight by releasing the balloon at 36. The separate power source 13 mayadvantageously comprise a very small environmentally acceptable batterysuch as an alkaline watch battery.

The present invention solves certain past needs. This inventiondescribes a system, method and design for use with lighter-than-airplatforms that overcomes certain safety drawbacks of conventionalunmanned lighter-than-air ballooncraft. The processor reduces oreliminates the chance of the platform becoming a free floating,uncontrolled transmitter by monitoring sensed coordinates and platformvelocities (GPS, star tracker, etc) and by comparing the sensedinformation to known (stored, programmed or calculated) geographic oraltitude based boundaries. If the processor determines that the platformis out of it's proper boundaries, termination is started. If the GPSfails, the processor also initiates termination. If the processorfunction unacceptably fails or if the primary power fails, terminationand recovery is also automatically initiated with a secondarytermination control circuit having its own small and environmentallyacceptable power source. This does not require power from the primarypower source of the platform.

Termination and recovery comprise several steps or actions as follows:

Releasing all Ballast to Reduce the Payload Density and Weight.

The following device allows for the controlled release of ballast (andgeneration of lifting gas) to reduce the ascent rate or slow down thedescent rate. At termination, all ballast is released automaticallyaccording to a mechanism as schematically depicted in FIG. 2. Ballastsystem and release mechanism

Both reactant A in Chamber A (100) and reactant B in Chamber B (101) ismetered into the reaction chamber (104) where hydrogen generationoccurs. The relative size of each of the two chambers is determined bythe molar ratio of the reaction. If water is used as one of thereactants and a fuel cell is used on the platform for generating power,the water byproduct of the fuel cell's reaction may be used for theballast system reaction as one of the reactants. Different meteringrates would be required for each reactant if the molar ratio of thereactants were not 1 to 1. This could be done with a dual peristalsispump (102) if the tubing diameters were adjusted to pump the appropriateamount from each reactant chamber. During the reaction, hydrogen isvented from the reaction chamber through a tube (107) into the balloon.A one-way valve (106) in the tube to the balloon prevents hydrogen fromflowing back into the reaction chamber. After the reaction is complete,the byproduct is dropped as ballast from the bottom of the reactionchamber (104) through an electrically actuated valve (105). The valve(105) is then closed. Upon flight termination, the reactants will bereacted as quickly as safely possible in the reaction chamber (104) andthe byproducts dropped as ballast.

In a second configuration (not depicted), the ballast system comprisestwo cavities each containing one of the two reactants. The reactant inthe top cavity is metered into the lower cavity where the hydrogengeneration occurs. The reaction byproducts are only released as ballastwhen all of the original reactants are depleted.

In a third configuration, a hydrocarbon chain is reformed to producehydrogen. This requires a catalyst such as platinum. Methods ofreforming hydrocarbons to produce hydrogen are well known in theindustry. The hydrogen is added to the lifting container and theremaining reacted reactants as dropped as ballast.

This method of hydrogen generation from the materials used for ballasteffectively makes the payload lighter and therefore safer in the eventof collision with aircraft or persons and property on the ground. Whileany acceptable ballast could be released, the novel ballast systemdescribed above effectively reduces the actual weight of ballastrequired by a system thereby increasing the safety of the payload. Inthe novel ballast system the total amount of ballast carried to providelong duration flight at an acceptable altitude is significantly reduced.Reducing the amount of ballast should in most cases increase safety. Inone specific example, the system uses water and either Sodium Hydride orCalcium Hydride as the ballast. When additional altitude is required, aquantity of water is added to a quantity of Sodium Hydride or CalciumHydride. A large volume of hydrogen gas is generated. This hydrogen isadded to the lifting balloon and the byproducts of the reaction aredropped as ballast. The platform becomes lighter due to the dropping ofthe Ca(OH)2 or Na(OH)2 byproduct and at the same time, hydrogen is addedto the balloon increasing lift. Only 73% (75% for Sodium Hydride) of anequivalent weight of inert ballast such as sand is needed. As ballastcan be a significant portion of the initial total weight, reducing theweight of the ballast significantly reduces the total weight of thepayload.

Releasing the Neck of the Balloon from the Platform to Initiate a QuickDescent.

This makes sure the platform descends quickly through the atmospherethereby reducing the potential time the payload passes through thecommercial air lanes. Small balloon systems such as the NWS weatherballoons rely on the balloon bursting due to expansion as it risesthrough the atmosphere. A hovering balloon does not experience thisexpansion and therefore must either have a system to burst the balloonor physically separate from the balloon. Venting the balloon isgenerally not acceptable because of the danger of the partially inflatedballoon drifting laterally on the ground increases the chance ofpersonal or property damage. A further problem would occur if hydrogenwas used as the lifting gas. This could create a possibility of hydrogenremaining in the balloon after landing and contacting an ignitionsource. Bursting the balloon is also generally undesirable as a burstballoon still attached to the payload may foul the descent mechanismcausing an uncontrolled descent. In the invention, the neck of theballooncraft is released when power is lost or the processor failseliminating these potential problems.

One possible implementation of the neck release mechanism as depictedschematically in FIGS. 3 and 4, comprises two concentric neck connectiontubes (43) and (49). The top tube (43) is slid into and attached to theballoon (41) with a strap (42) or rubber band (42) and fits within thebottom tube (49), which is attached to the payload (51). The top tube(43) is restrained from sliding out of the bottom tube (49) by a pieceof monofilament line (47). While top tube (43) and bottom tube (49) arerestrained to each other, flexible seal (44) prevents gas in the tubesfrom leaking at the junction of the tubes. Each end of the monofilamentline (47) is threaded through a small hole in flange (46) and tied off.The monofilament line (47) is threaded around two knobs (52) and alsothrough and in contact with an electrically resistive coil (48).

A second implementation of the neck release mechanism utilizes a tubethat is attached to the neck of the balloon as in the firstimplementation. The tube is removably attached to the payload by one ormore latches. When these latches are undone, the neck can separate fromthe payload.

In a third implementation of the neck release mechanism, a tube that isattached to the neck of the balloon as in the first implementation isaxially aligned and slides within or over the second tube that isattached to the payload. A release pin or pins passes through both tubesfrom the side such that when the pin is removed, the tubes are free toseparate from each other. See FIG. 11.

When termination of the flight is called for, the ballast is preferablyreleased first and then a current is passed through the resistive coil(48). The coil heats (48) up and melts through the monofilament line(47). The weight of the payload (51) now pulls the bottom tube (49) fromthe top tube and the payload is released from top tube (43).and thusfrom the balloon (41). This ballast system advantageously allows for theventing of the lifting gas directly at the payload eliminating the needfor wiring to remote valves.

The Battery Discharge and Neck Release Circuit.

The battery discharge and neck release circuit is schematically depictedin FIG. 5. The processor must constantly supply a keep alive signal tothe battery discharge circuit in order to prevent the batteries fromdischarging. This keep alive signal comprises a square wave. The batterydischarge circuit senses the low to high transitions in the keep alivesignal and resets the timer (a HEF 4060) each time a transition isdetected. The timer must be reset by the presence of the keep alivesquare wave or the timer will end it's counting and initiate the batterydischarge. A high power FET closes the circuit that discharges thebatteries. In one implementation of the discharge circuit, the powerfrom the discharge circuit comes from the main batteries themselves.Because the discharge circuitry can function down to extremely lowbattery voltages, the batteries are effectively discharged by the timethe discharge circuit is unable to function.

An alternate implementation uses a separate, non-hazardous, smallbattery to operate the discharge circuitry. This implementation ensuresthat the main batteries are completely discharged. The discharge circuitdissipates power through the resistive wire that during batterydischarge, dissipates the energy as heat. The resistive wire is wrappedaround a piece of monofilament (fishing) line. When the battery power isdissipated through the resistive wire, the monofilament line is meltedthrough and the neck connecting the balloon to the platform is releasedfrom the payload. Another advantage of providing a separate power sourcefor the discharge circuit is that the discharge circuit battery willsupply the resistive element with power to cut the monofilament lineeven if the main batteries are dead. As an alternative, the dischargecircuit could dissipate power through a high power resistor if the neckrelease function were not used.

If the processor senses any of the conditions necessary to initiatetermination, it ceases sending the keep alive signal to the dischargecircuit. If the processor dies or the power fails, the keep alive signalalso ceases, causing termination. The timer advances to a point where itinitiates the battery discharge. Battery current flows through theresistive wire discharging the batteries and melting through themonofilament to release the balloon neck. The battery dischargecontinues until the main batteries are completely dead.

The main platform batteries are fully discharged during descent topositively prevent further radio transmission. Once discharge isinitiated, the batteries fully discharge. The processor can initiate thebattery discharge as described above or automatically when power orprocessor control is lost. It has been found that long duration flightat high altitudes and cold temperatures requires special high-densitybatteries. It has been found that lithium batteries beneficially fulfillsuch requirements. Additionally, it was found that the EnvironmentalProtection Agency (EPA) states that lithium based batteries areconsidered hazardous waste except for one type of cell and only whenfully discharged. Particularly it has been found that Lithium SulfurDioxide (LiS02) batteries, when fully discharged, form a lithium salt,which is not considered hazardous by the EPA. Automatically dischargingthe LiS02 batteries before they contact the ground not only prevents thetransmitter from transmitting but also renders the batteriesnon-hazardous.

The “Maple seed” Descent Device.

Use of a novel and integral “maple seed” like descent device to increasesafety is depicted in FIGS. 6, 7 and 8. A single airfoil shaped bladeattached to the bottom of the platform causes autorotation of thepayload and airfoil blade upon rapid descent. This replaces atraditional parachute with a highly reliable decelerator that isgenerally immune to fouling and requires no deployment mechanism and isalso immune to fouling problems with animals and property after descent.The “maple seed” decelerator may also be used to conveniently house theantenna.

This autorotation occurs because of the asymmetrical nature of theairfoil. The center of mass of the payload/airfoil combination isshifted well to the payload end while its center of lift isapproximately in the middle. This causes a circular rotation of theentire assembly around its center of mass. The rotation actuallyinscribes a cone around the axis of fall. The shape of the cone willvary depending upon the aerodynamic qualities of the airfoil. An airfoilwith minimal lift properties will inscribe a steep-side cone while anairfoil with strong lift properties will inscribe a very flattened cone.

Platform Recovery.

A novel method of platform recovery is depicted in FIG. 9. To aid in therecovery of the platform, the landed platform transmits its lastrecorded position to an additional airborne platform. The platform coulddetermine that it had landed by comparing sequential position readingsand noting when they consistently indicate no change in position. Thesecond platform relays the current location of the landed platform to aground station where the position of the landed platform is used to aidin recovery of the landed platform. A GPS unit on the landed payloadcould determine the position of the landed platform. The transmissionfrom the landed platform to the additional airborne platform couldutilize nearly any commercially available or custom transceiver.

The “Handoff” Mechanism.

FIG. 10 shows the capability of handoff, i.e., handing off signal,between platforms by the communications devices. FIG. 10 shows aschematic view of a portion of a constellation and communication networksystem in which 12(i), 12(ii) arid 12(iii) airborne platforms. Each airborne platform comprises a lighter than air gas enclosure such as aballoon, and a transceiver (processor). Strong and weak signals betweenplatforms and the communication devices (user equipment) 22 v-z, locatedon or above ground, are shown by solid and dashed lines 120. Thetracking antennas 126 could be located on ground terminal 124 orplatform launcher, i.e., SNS launcher 46. Also, on the SNS launcher 46could be a launcher 44. Lines 28 show the command and control linkbetween the tracking antennas 126 and platforms.

In particular, FIG. 10 shows communication devices 22 y and 22 zcommunicating with platforms 12(ii) and 12(iii). The signal fromplatform 12(iii) is stronger (as shown by solid lines) than that fromplatform 12(ii) (as shown by dashed lines). When platforms 12(ii) and12(iii) migrate from left to right due to wind currents as shown in FIG.10, communications devices 22 y and 22 z hand off communication withplatform 12(iii) to platform 12(ii) as platform 12(iii) moves out of thecommunication range and platform 12(ii) moves to the former position ofplatform (iii). Generally, the processor(s) on board the platform(s)does not hand off the signal; it is the communication device(s) thatinitiates the handoff.

The communications signal transceiver comprises circuitry capable ofcommunications using FDMA, TDMA, CDMA, and ReFLEX protocols. All ofthese named protocols use “handoff.” For example, U.S. Pat. No.5,649,000, issued Jul. 15, 1997, discloses a method and system forproviding a different frequency handoff in a CDMA cellular telephonesystem. Devices using these protocols periodically scan for neighboringcontrol channel in the background, without interrupting normaloperations. If the device finds a better channel, in terms ofsignificantly better signal strength or higher priority, it can requesta transfer. This is usually done using “make before break,” a conceptsimilar to the soft hand-off used in PCS phone networks, whereregistration with a new channel is completed before communication withthe old channel is broken. Normally, this means that a device willalways be registered with the network, and capable of receivingmessages. This permits communication devices to move quickly andefficiently across service areas with different control channels.

Another embodiment is a floating constellation communication systemcomprising a plurality of lighter-than-air platforms, each including analtitude regulator device to control the floating of said platformswithin a predetermined altitude range, each platform carrying at leastone communication signal transceiver; a plurality of geographicallyspaced-apart platform launching sites from which said plurality ofplatforms can be launched; a plurality of ground terminals capable oftracking one or more of said plurality of platforms, said groundterminals capable of transmitting communication signals to and capableof receiving communication signals from at least one of said pluralityof communication signal transceivers carried by said plurality ofplatforms; a network of communication links interconnecting said groundterminals to one another; and a plurality of coded communication deviceswithin a contiguous geographic area, said coded communication deviceshaving communication capabilities compatible with the capabilities ofsaid signal transceivers carried by said platforms.

Another embodiment is a floating constellation of communicationplatforms comprising a plurality of separately launchablelighter-than-air platforms capable of initially ascending into theEarth's atmosphere after being launched; each of said plurality ofplatforms further comprising an altitude regulator operatively connectedto regulate each of said platform to float within a predeterminedaltitude range after initial ascent; and a communication signaltransceiver carried by each of said plurality of platforms.

Another embodiment is a floating constellation communication systemcomprising a plurality of lighter-than-air platforms regulated to floatwithin a predetermined altitude range, each platform carrying at leastone communication signal transceiver; a plurality of geographicallyspaced-apart platform launching sites from which said plurality ofplatforms can be launched; a space satellite and a network of satellitecommunication links between a plurality of ground terminals capable ofsaid space satellite and of said plurality of platforms, and capable oftransmitting communication signals to and receiving communicationsignals from said plurality of communication signal transceivers carriedby said plurality of platforms; a network operations center (NOC) and asatellite communications link between said NOC and said space satellitethereby interconnecting said NOC and said plurality of platforms; and aplurality of coded communication devices within a contiguous geographicarea having communication capabilities compatible with capabilities ofsaid communication signal transceivers carried by said plurality ofplatforms.

Another embodiment is a floating constellation of communicationplatforms comprising a first plurality of airborne platforms regulatableto ascend and float in the air for a period of time within apredetermined range of altitudes, said first plurality of airborneplatforms ascending at a first time from geographically spaced-apartlocations; a next plurality of airborne platforms regulatable to ascendand float in the air within said predetermined range of altitudes, saidnext plurality of airborne platforms ascending at a next time from saidgeographically spaced-apart locations; a rapid deflation system forremoving said airborne platforms from the air upon malfunction orimproper location of said airborne platform; at least one platformcommunications signal transceiver attached to each of said airborneplatforms; a plurality of geographically spaced-apart groundtransceivers capable of communication with said airborne platform; anetwork of communication links interconnecting said plurality of groundtransceivers; and a plurality of coded devices having communicationcapabilities corresponding to the capabilities of said platforms andselectably addressable by communication signals from said platforms.

Yet another embodiment is a floating constellation of communicationplatforms comprising a plurality of airborne platforms regulatable tofloat within an adjustable altitude range and spaced apart to providesubstantially ubiquitous line-of-sight coverage over a contiguousgeographic area; said plurality of airborne platforms including aplurality of communication transceivers, at least one of said pluralityof communication transceivers carried by each of said plurality ofairborne platforms; a plurality of ground terminals spaced-apart oversaid contiguous geographic area for maintaining substantially ubiquitousline-of-sight signal communication between said communication devices ofsaid plurality of airborne platforms and said ground terminals; anetwork of communication links interconnecting said plurality of groundterminals; and a plurality of coded devices capable of communicationswith said plurality of communication transceiver and addressable fromone or more of said plurality of platform-carried communicationtransceivers.

Another embodiment is an airborne constellation comprising a pluralityof individual lighter-than-air platforms spaced apart above a contiguousgeographic area so that substantially ubiquitous line of sight coverageof said geographic area is provided; each of said plurality of platformscomprising an enclosure holding a regulated volume of low density gas sothat the total density of said platform is lower than the atmosphericair up to a predetermined altitude range; and each of said plurality ofplatforms further comprising a signal transmitting device attached tosaid enclosure by which signals from said platform may be transmitted tosaid contiguous geographic area.

Another embodiment is an altitude regulated lighter-than-aircommunications platform comprising a low density gas enclosure forholding a quantity of low density gas; a transceiver attached to saidenclosure including electronic circuitry and an onboard electrical powersource; and an altitude regulator attached to said platform to regulatethe altitude of said platform within a predetermined altitude range,said altitude regulator comprising an altitude determining mechanism; acontrollable vent from said gas enclosure and vent controls operativelycoupled with said altitude determining venting of gas for regulating thealtitude of said platform; and a controllable ballast release attachedto said platform and ballast controls coupled with said altitudedetermining mechanism to release ballast for regulating the altitude ofsaid platform.

Another embodiment is a free floating constellation communicationssystem comprising a plurality of lighter-than-air platforms comprisingat least a first platform and a second platform, the first and secondplatforms comprising a communications signal transceiver and being freefloating without any longitudinal and latitudinal position control; anda plurality of communications devices within a contiguous geographicarea, at least one of the communications devices having communicationscapability with the communications signal transceiver; wherein the atleast one of the communications devices is capable of handing offcommunication with the first platform to the second platform as thefirst platform moves out of a communication range of the at least one ofthe communications devices, and wherein the free floating constellationcommunications system provides a line-of-sight coverage of wireless datato a population on a contiguous landmass and the plurality oflighter-than-air platforms are launched in a manner such that when in anoperating range of 60,000 to 140,000 feet there is substantially arelative distance between the plurality of lighter-than-air platforms.The free floating constellation communications system (CCS) couldfurther comprise an altitude regulator device; plurality ofgeographically spaced-apart platform launching sites from which theplurality of platforms can be launched; a plurality of ground terminals;and a network of communications links interconnecting at least some ofthe ground terminals to one another. Preferably, the regulator isoperatively connected to regulate the platform to float within thestratosphere of the Earth. Preferably, a predetermined altitude rangewithin which the plurality of platforms is regulated to float comprisesa range of about 70,000 feet to about 100,000 feet. The regulatorregulates the floating of the platform within a predetermined altituderange and comprises a quantity of contained gas having a density lessthan the density of air within the predetermined altitude range and acontrollable vent by which a portion of the quantity of contained gascan be released to reduce the buoyancy of the platform. The regulatorcomprises a quantity of high density material carried onboard theplatform and a release device by which a portion of the high-densitymatter can be released to increase buoyancy of the platform. Preferably,the regulator comprises: a controllable gas vent; a controllable ballastrelease device; an altitude determining mechanism; and a control signalprocessor device connected with the transceiver, the altitudedetermining mechanism, the gas vent and ballast release so that thealtitude can be adjusted.

Preferably, the communications system of the plurality of spaced-apartground terminals comprises a transceiver. The CCS could further comprisea tracking device, wherein the tracking device comprises: a directionalantenna; and a directional antenna aiming mechanism responsive to GPScoordinate data for selectively aiming the directional antenna at one ormore of the plurality of platforms. The tracking device comprises: adirectional antenna; and a directional antenna aiming and gain trackingmechanism for aiming the directional antenna at a selected platformaccording to communication signal strength between the selected platformand the directional antenna. Preferably, at least one of thespaced-apart ground terminals comprises a network operation center.

The CCS could further comprise a network operation center (NOC)connected to the network of communications links. Different variationson NOC connections are the following. The NOC is connected to at leastsome of the plurality of ground terminals with a hub and spokearrangement of communications links. The NOC is connected to at leastsome of the plurality of ground terminals with a mesh arrangement ofcommunications links.

Other variations are the following. The network of communications linksinterconnecting the ground terminals comprises connections to groundlines. The network of communications links interconnecting the groundterminals comprises space satellite communications links. The network ofcommunications links comprises platform-to-platform communicationslinks.

Other variations include the following. The plurality of platformscomprise a lighter-than-air device selected from the group consisting ofa balloon, a blimp, an aerostat, a zeppelin, an airship, a dirigible, aweather balloon, a jimsphere, a hot air balloon, a sounding balloon anda meteorological balloon and combinations thereof. The plurality ofplatforms comprises rubber balloons. The platforms have zero-pressureballoons, internal air bladder balloons, adjustable volume balloons orhydrogen-filled balloons.

Other variations include the following. The communications devicesinclude pagers, advanced messaging devices, wireless telephones,telemetry devices or equipment tracking units. [0088] Still othervariations include the following. The platform comprises a rapid descentmechanism; and the platform is disposable. The platform comprises aballoon; the platform comprises a rapid descent mechanism; and theballoon is replaceable for recovery and reuse of the transceiver.

Yet other variations include the following: The communications signaltransceiver comprises circuitry capable of communications usingFrequency Division Multiple Access (FDMA) protocol, Time DivisionMultiple Access (TDMA) protocol, Code Division Multiple Access (CDMA)protocol, the ReFLEX protocol, the Flex protocol the POCSAG pagingprotocol, or the ERMES paging protocol.

The CCS could further comprise an altitude determining mechanism; asource of meteorological data; and controls for adjusting the altitudeof a platform into a wind velocity and direction determined according tothe meteorological data.

The CCS could further comprise an attitude sensor onboard at least onethe plurality of platforms; and a steerable antenna coupled to at leastone of the communications signal transceivers and attached to at leastone of the plurality of platforms, the steerable antenna havingstabilization controls for stabilizing the steerable antenna in adirection from the platform provides consistent ground coverage over thegeographic area and an aim control operatively associated with thesteerable antenna and the altitude sensor for selectively changing theposition of the coverage area of the antenna to facilitate filling gapsof coverage over the geographic area.

The CCS could further comprise an unmanned free balloon; and a payloadbox having a total weight less than six pounds and exterior surfaceswith predetermined areas and that has a weight to size ratio of no morethan three ounces per square inch on any surface of the package,determined by dividing the total weight in ounces of the payload box bythe area in square inches of its smallest exterior surface.

Other variations include the following. At least one of the plurality ofplatforms further comprises an altitude regulator operatively connectedto regulate the platform to float within a predetermined altitude rangeafter initial ascent; wherein the altitude regulator further comprises:a quantity of high density material; a device for determining thealtitude of the platform, wherein the device for determining thealtitude of the platform comprises a global positioning system (GPS)receiver; and a material release mechanism for releasing a portion ofthe quantity of high density material.

The CCS could further comprise a hydrogen gas enclosure for holding aquantity of hydrogen; an onboard electrical power source on at least oneof the platforms, wherein the on-board electrical power source comprisesa fuel cell interconnected with the hydrogen gas enclosure for receivinghydrogen as a component of the fuel for the fuel cell; and an altituderegulator attached to the platform to regulate the altitude of theplatform within a predetermined altitude range, the altitude regulatorcomprising: an altitude determining mechanism; a controllable vent fromthe gas enclosure and vent controls operatively coupled with thealtitude determining mechanism for venting of the hydrogen gas forregulating the altitude of the platform; and a controllable ballastrelease attached to the platform to release ballast for regulating thealtitude of the platform. In variations thereof, the controllable ventand vent controls are operatively coupled thereto further comprise atleast one Nickel-Titanium (NiTi) element mechanically coupled to thecontrol vent and operatively connected to the electrical power sourcefor selectively receiving and not receiving electrical power to therebyselectively change the length of the NiTi element for opening andclosing the controllable vent. The CCS could further comprise ameteorological package connected to the platform through a fiber opticlink to the transceiver thereby substantially preventing electricalarcing between the meteorological package, the transceiver when theplatform moves through electrically charged clouds and a tracking systemcapable of tracking one or more of the plurality of platforms.

Other variations include the following. The network operation centercomprises circuitry for controlling a predetermined operation of theplatform.

The CCS could further comprise a rapid deflation system for removing aplatform from the air upon malfunction or improper location of theplatform.

Another embodiment is a free floating constellation communicationssystem comprising a plurality of lighter-than-air platforms comprisingat least a first platform and a second platform, each of the first-andsecond platforms comprising a communications signal transceiver andbeing free floating without any longitudinal and latitudinal positioncontrol; and a plurality of communications devices within a contiguousgeographic area, at least one of the communications devices havingcommunications capability with the communications signal transceivers;wherein the at least one of the communications devices is capable ofreceiving communications from the communications signal transceiver ofthe first platform and the communications signal transceiver of thesecond platform, but hearing communications from only one communicationssignal transceiver and the plurality of lighter-than-air platforms arelaunched in a manner such that when in an operating range of 60,000 to140,000 feet there is substantially a relative distance between theplurality of lighter-than-air platforms.

Yet another embodiment is a free floating constellation communicationssystem comprising a plurality of lighter-than-air platforms comprisingat least a first platform and a second platform, each of the first andsecond platforms comprising a communications signal transceiver andbeing free floating without any longitudinal and latitudinal positioncontrol; and a plurality of communications devices within a contiguousgeographic area, at least one of the communications devices havingcommunications capability with the communications signal transceivers;wherein the first and second platforms dynamically assign new frames inwhich to transmit communication signal from the communications signaltransceiver as the platforms drift such that a communications devicereceives communications signals from only one communications signaltransceiver in a particular frame and the plurality of lighter-than-airplatforms are launched in a manner such that when in an operating rangeof 60,000 to 140,000 feet there is substantially a relative distancebetween the plurality of lighter-than-air platforms.

Yet another embodiment is a method of communicating using a freefloating constellation communication system comprising providing acommunication device for communicating with lighter-than-air platforms;communicating with a first lighter-than-air platform when thecommunication device is in a communication range of thefirst-lighter-than-air platform, communicating with a secondlighter-than-air platform when the communication device moves out of thecommunication range of the first lighter-than-air platform, wherein thefirst and second lighter-than-air platforms each comprise an altituderegulator device and a communications signal transceiver and wherein thefirst and second lighter-than-air platforms are free floating withoutany longitudinal and latitudinal position control and the plurality oflighter-than-air platforms are launched in a manner such that when in anoperating range of 60,000 to 140,000 feet there is substantially arelative distance between the plurality of lighter-than-air platforms.

Yet another embodiment is a method of communicating using a freefloating constellation communications system comprising providing aplurality of lighter-than-air platforms comprising at least a firstplatform and a second platform, each of the first and second platformscomprising a communications signal transceiver and being free floatingwithout any longitudinal and latitudinal position control; andcommunicating with a communication device having communicationscapability with the communications signal transceiver, wherein the firstand second platforms dynamically assign new frames in which to transmitcommunication signals from the communications signal transceivers as theplatforms drift such that a communication device receives communicationssignals from only one communications signal transceiver in a particularframe and the plurality of lighter-than-air platforms are launched in amanner such that when in an operating range of 60,000 to 140,000 feetthere is substantially a relative distance between the plurality oflighter-than-air platforms.

Another embodiment is a method for providing communication servicecomprising providing a first lighter-than-air platform; providing asecond lighter-than-air platform, wherein the first and secondlighter-than-air platforms each comprise an altitude regulator deviceand a communications signal transceiver and wherein the first and secondlight-than-air platforms are free floating without any longitudinal andlatitudinal position control; providing a plurality of communicationsdevices within a contiguous geographic area, at least one of thecommunications devices having communications capability with thecommunications signal transceiver, wherein the at least one of thecommunications devices is capable of handing off communication with thefirst platform to the second platform as the first platform moves out ofa communication range of the at least one of the communications devicesand wherein the free floating constellation communications systemprovides a line-of-sight wireless data coverage to a population on acontiguous landmass and the plurality of lighter-than-air platforms arelaunched in a manner such that when in an operating range of 60,000 to140,000 feet there is substantially a relative distance between theplurality of lighter-than-air platforms.

Variations include the following. The communication device comprises apager, an advanced messaging device, or a wireless telephone. Thealtitude regulator device regulates the altitude of the platform towithin a predetermined altitude range of between about 60,000 feet andabout 140,000 feet. The altitude regulator device is operativelyconnected to regulate the platform to float within the stratosphere ofthe Earth. The altitude regulator regulates the floating of the platformwithin a predetermined altitude range and comprises a quantity ofcontained gas having a density less than the density of air within thepredetermined altitude range and a controllable vent by which a portionof the quantity of contained gas can be released to reduce the buoyancyof the platform. The altitude regulator comprises a quantity of highdensity material carried onboard the platform and a release device bywhich a portion of the high-density matter can be released to increasebuoyancy of the platform. The altitude regulator device is operativelyconnected to regulate the platform to float within the stratosphere ofthe Earth. The altitude regulator regulates the floating of the platformwithin a predetermined altitude range and comprises a quantity ofcontained gas having a density less than the density of air within thepredetermined altitude range and a controllable vent by which a portionof the quantity of contained gas can be released to reduce the buoyancyof the platform. The altitude regulator comprises a quantity of highdensity material carried onboard the platform and a release device bywhich a portion of the high-density matter can be released to increasebuoyancy of the platform. The altitude regulator comprises a quantity ofhigh density material carried onboard the platform and a release deviceby which a portion of the high-density matter can be released toincrease buoyancy of the platform.

FIG. 12 depicts a schematic view of a portion of a constellation andcommunication network system 10 according to the present invention inwhich airborne platforms 12(a)-(g) have reached a desired altitudewithin a range of altitudes, such as in the stratosphere. Also depictedis an airborne platform 12(h) in the process of ascending to a desiredaltitude. Each airborne platform comprises a lighter-than-air gasenclosure 14(a)-(h), a platform control and communicator device16(a)-(h) and an antennae 18(a)-(h). Platform-to-ground communicationsignals are schematically represented at 20(a)-20(u) correspondinglycommunicating with a plurality of ground communication devices such asradio signal receivers, transceivers, transmitters, or pagers22(a)-22(u). There are a plurality of launch and tracking terminals24(a)-(d), each having a plurality of tracking antennas 26(a)-(o).Ground terminals relay message and control data between the SNSplatforms and the NOC. Preferably the ground terminals can operateunattended requiring only electrical power and communications signals.The ground terminals consist of a set of transmitters and receivers andtheir controller, tracking antennas and a tracking controller, redundantcommunications links to the NOC, and backup power supply. To accommodatethe potentiality for several platforms within range at any given timefour to six separate transmitters, receivers and tracking antennas arecurrently contemplated. Both Genera and Motorola offer appropriatecommercially available transmitters, transmitter controllers andreceivers for the SNS ground terminals although some modifications willbe required. The tracking antennas 26 are schematically shown incommunication with the various platforms through ground-to-platformsignals 28(a)-(g). A ground communication network 30, havinginterconnecting segments 30(a)-(d) are depicted communicating betweenthe launch and tracking stations 24(a)-(d) and a network operationscenter 40. The network operations center 40 may also communicate with aplurality of launch and tracking terminals 24 through an orbitingsatellite 32 and launch site satellite antennas 38(a)-(d) and networkoperation center satellite antenna 42. For purposes of illustration,launch and tracking terminal 24(c) is co-located with an airborneplatform launcher 44 similar to or the same as the National WeatherService balloon launcher. One aspect of the invention also contemplatesa mobile launcher and tracking terminal 46, as for example aself-contained unit mounted on a truck trailer. The mobile launcher canbe transported to a desired launch site, parked there and additional SNSplatforms can be launched. The tracking and communication terminals 24can be connected to the network via ground links 30(c) and 30(d), aswell as to other launch stations and to the network operations center40. The mobile launcher and terminal may be moved periodically from onelocation to another location to launch and/or track additional SNScommunication platforms 12(a) as needed to fill in coverage gaps as theymight arise due to weather conditions.

FIG. 13 is an enlarged schematic depiction of the mobile SNS launcher 46of FIG. 12 shown schematically in relationship to platforms 12(f), 12(g)and 12(e) that form a portion of the constellation of platforms. Themobile SNS launcher is in communication with the network operationscenter 40. Further depicted in FIG. 12 is a range of desired altitudes50 defined by a minimum desired altitude 48 and a maximum desiredaltitude 52, each altitude measured relative to sea level 54. In onepreferred embodiment, a minimum desired altitude of about 60,000 ft. anda maximum desired altitude of about 140,000 ft define a predeterminedrange of altitudes. These altitudes generally correspond to the Earth'sstratosphere or to a range of stratospheric altitudes 50. Furtherdepicted in FIG. 12 is a gap of coverage 56 between spaced-apartplatforms 12(g) and 12(e) schematically represented as a spaced-apartdistance 56 that is significantly larger than the desired spaced-apartdistance 58 between platforms 12(f) and 12(g). In a further preferredembodiment, it is anticipated that platforms will be regulated to floatwithin a predetermined altitude range of between about 70,000 ft. and100,000 ft. will have a coverage radius measuring about 175 miles (280km) will be above commercially regulated airspace and will be belowaltitudes at which platform survival is less certain. When the distancebetween two adjacent platforms in any direction is greater than aboutone and one-half times the coverage radius, a gap in coverage can beginto occur. In such instances, a mobile launching unit 46 can be moved onthe ground to a location substantially between the two spaced-apartplatforms 12(g) and 12(e) so that an additional supplemental platform12(h) may be launched for rapid ascent to the desired altitude range 50.Computer modeling based upon the tracking of all the platforms 12 in aconstellation 10 of airborne platforms can be used to predict thedevelopment of significant gaps 56 in coverage and to rapidly deploymobile launching units to fill the gaps. In the event that a stationarylaunching and tracking terminal is already in a location for launching asupplemental SNS platform, no mobile unit would be required.

FIG. 14 is a schematic depiction of inter-platform communications withsubsequent transmission to ground terminals and to a network operationcenter (NOC).

FIG. 15 is a schematic depiction of platform-to-space satellitecommunication links for providing the network interconnection with anetwork operation center (NOC).

FIG. 16 is a schematic depiction of a “hub and spoke” networkcommunication link topography. This is advantageous because it isgenerally less total communication lines and generally less expensiveequipment than by providing a ring topology.

FIG. 17 is a schematic depiction of a mesh network communication linktopography. Ring topology essentially daisy chains all of the groundstations together in one, big ring of communications links. This ring isgenerally considered to lack robustness. If one or two points go down onthe ring, it could isolate otherwise functioning ground terminals.

FIG. 18 schematically depicts a contiguous geographic area 100, and inparticular by way of example, a geographic area corresponding to theUnited States of America. Superimposed on the geographic area 100 are70-selected standard launch sites represented by “Xs” 101-170. Furtherschematically depicted are coverage areas 201-270 representing theposition and coverage of each of the platforms 101-170 as they reach adesired regulated altitude, preferably in the stratosphere. Eachplatform is very small compared to existing synchronous orbit satellitessuch that they have been referred to and are designed to float in aregulated altitude in the stratosphere such that they have beendesignated as “stratospheric nanosatellites” (SNS). The coverage areas201-270 are depicted in FIG. 14 assuming a relatively vertical ascentfrom the launch sites 101-170. The coverage areas 201-270 will migrateover a period of time, due to wind and weather conditions in aparticular locality. However, the ascent to the stratospheric desiredaltitudes normally takes from about one to two hours, such that thedrift for normal airspeeds of less than about 10-20 mph and even passingthrough the jet stream if present will produce relatively small driftsof 10-80 miles in any direction during the ascent. Thus, relative to theapproximately 175-mile (280 km), coverage radius for a circular coveragearea having a diameter of about 350 miles (560 km), the migration duringa short period of time with standard wind conditions of 10-40 miles,indicates that the launch site is a reasonable approximation for theinitial high altitude location at the end of the ascent.

The platform for balloons 12 are provided with altitude controlmechanisms, including both low density gas venting and high densityballast dropping mechanisms, allowing the balloon to be controlled tomaintain a desired altitude within a range of desired altitudes. Thealtitudes may be maintained for between 12-24 hours corresponding to thecurrent NWS balloon-launching schedule of two launches per day. If theNWS launching schedule is not used, the balloon altitudes may bemaintained for over 100 hours depending on the lift gas, power, andballast remaining on the balloon 12. In the case of NWS balloons,currently the balloons self-destruct from overexpansion as they reachand exceed altitudes of over 100,000 ft. and weather data is gatheredand transmitted to the ground during the ascent. In the case of balloonsacting as carriers for the communication platforms, the platforms willbe maintained at an altitude preferably less than 140,000 ft. And morepreferably less than about 100,000 ft. and will continue to migrate dueto upper stratospheric wind conditions. The NOC may command a SNSplatform to rapid deflate or burst in the case of a balloon 12, when theplatform is no longer needed, it falls below the 60,000 ft. and noballast remains, it drifts over an undesired area, or it malfunctions.The platform may initiate this if any of these conditions are met andthe platform has lost communication with the ground terminals.Advantageously, the wind conditions will have been detected during theascent and will continue to be monitored through the tracking by theground stations. This will facilitate predicting the development of anygaps in coverage that might be expected, and particularly the locationof such gaps and the number of ground communication devices or pagersthat might need to be serviced in the area of the gap.

FIG. 19 is a schematic depiction of the geographic area 100 after agiven migration time period during which significant gaps may begin tooccur. Mobile units may be positioned at temporary launch sites 171 and172 for filling developing gaps 56(b) and 56(c). Also, where a gap ispredicted to develop in close proximity to a standard launch site, as,for example, at 105, an additional platform may be launched from launchsite 105 in advance of the normally regular launch time period. Thus,gap 56(c). In a similar manner, a plurality of typically regionallylocated mobile launch sites may be employed to fill gaps as they arise.In the event that a pattern of gap development is detected, thenadditional permanent launch sites 173 and 174 may be added to helpcompensate for repeated developments of gaps 56(d) and 56(e), forexample. Temporary launch sites may be moved seasonally to fill the gapsalong the coast line along the direction the wind is blowing for theseason, for example, the western coast during the winter season.

FIG. 20 shows a schematic side elevation view of a platform 12 in anembodiment in which the low-density gas enclosure 70 is preferably alatex balloon 70. A Totex 1000 balloon filled with hydrogen andinternally coated to reduce hydrogen diffusion adequately provides liftfor the SNS communications platform. The Totex balloon is released witha diameter of about five and one-quarter feet and expands to abouttwenty-four feet across at 140,000 feet altitude. It will be noted thatother lighter-than-air enclosures, such as blimps, aerostats, zeppelins,airships, dirigibles, weather balloons, jimspheres, hot air balloons,sounding balloons or meteorological balloon might also be used in placeof the proposed latex weather balloon 70 schematically depicted in FIG.6. Also, the diameter of balloon 70 in FIG. 6 is not to scale and it isexpected that a total platform weight, including the payload box 300,altitude control vent mechanism 72, meteorological package 82, antennae76 and meteorological cable connection 84. Preferably the cable 84 is afiberoptic cable having a length of approximately 25 meters so that themeteorological data collection package 82 is sufficiently distanced fromthe balloon 70 to reduce to a minimum the effect of turbulence caused bythe balloon on the meteorological data sensed by the meteorologicalpackage 82. The fiberoptic cable 84 is used to transmit themeteorological data from meteorological package 82 to the communicationsunit 74. Fiberoptic cable is used as wire would arc due to the highelectric field potential when passing through thunderclouds.

There are numerous types of low-density gas enclosure devices, andparticularly balloons, that might be considered useful for the presentinvention. Among the potentially preferred types of balloons are rubberpressure balloons, zero pressure balloons, internal air bladderballoons, adjustable volume balloons and super pressure balloons. Eachtype of these balloons has different advantages and disadvantages and,for purposes of the present invention, it has been found that the rubberpressure balloon is most preferred and the zero pressure balloon is alsoconsidered a preferred alternative.

The rubber pressure balloons have a stretchable rubber membranecontaining the lifting gas that allows the balloon to increase in sizeas the external air pressure decreases as the balloon rises. This is themost common type of weather balloon and is also consistent with partyballoons. The primary advantage is the low cost and common accessibilityso that high quality balloons of this type, such as weather balloons,are available at low cost. These balloons are somewhat fragile and theyhave delicate handling requirements and also low extended reliability.Further, the use of such balloons requires venting of the lifting gas toprevent bursting upon reaching maximum altitudes.

The zero pressure balloons consist of an initially loose bag, usuallymade from a plastic such as polyethylene or Mylar. As the external airpressure decreases, the bag increases in volume. Once the bag reachesits whole volume, gas must be vented or the balloon will burst as thebag material does not stretch. Although this type of balloon may be morereliable than the rubber balloons and provide less diffusion of thelifting gas, it is of a median cost, more costly than the rubberballoons, currently between about four to ten times more expensive.Thus, although the rubber balloon might be more preferred for purposesof low cost platforms, the zero pressure balloon also provides a usefulenclosure for lifting the platform up and has certain advantages overthe rubber pressure balloons.

Internal air bladder balloons consist of a flexible balloon containingair enclosed in a fixed volume balloon contain a lifting gas. Air ispumped into the inner-flexible balloon, which compresses the lifting gastrapped in the fixed volume balloon, thereby decreasing the overalllift. Air is let out of the inner-flexible balloon to increase lift.Blimps adjust lift using this principle. This type of balloon hascertain advantages as there is no lift gas lost when reducing lift andit is potentially more reliable than rubber balloons, however it is morecostly due to extra balloon, pump and extra required power for operatingthe increase and decrease of lift mechanism.

Adjustable volume balloons consist of a fixed volume containing thelifting gas and a mechanical way of reducing the volume of the balloon.By decreasing the volume, the lifting gas is compressed and the liftdecreases. The volume may be reduced any number of ways, including anadjustable line inside the balloon from the top of the balloon volumedecreases. This has less diffusion of the lifting gas, theoretically,lifting gas is not lost when reducing lift and it may be more reliablethan rubber balloons. However, it has a significantly more costly due tothe mechanical volume reducing mechanism and further, requires extrapower for operation of such a mechanical volume-reducing mechanism.

Super pressure balloons have a fixed volume. They are called superpressure balloons because they do not expand to match the decreasingexterior pressure. They are built strong enough to hold the increasedpressure. The balloons can achieve extremely long float lies becausethey do not need to vent gas to prevent bursting and they typically havevery low membrane gas diffusion. This type of balloon is the highestcost, although one of the most reliable, with little loss of liftinggas. The extreme high cost and difficulty of manufacture and the lack ofdeveloped technology regarding such balloons, indicates that otheralternatives are currently more attractive.

A signal transmission antenna 76 extends from the communication device74 preferably vertically downward from the communication device 74 andpreferably a collinear array with approximately a 6 degree down tiltconfigured to provide even transmission and reception coverage over theentire circular coverage area. The antennae 77 may advantageously beprovided with a support loop 86 to facilitate stabilization between theantennae and the meteorological connection cable 84. Also depicted inFIG. 6 is a balloon destruct mechanism 78 and a parachute 80 forrecovery of the communication device 74, when the balloon is destroyedby the controlled destruct mechanism 78 or otherwise by natural causes.

[FIG. 21 depicts a partial cross-sectional front view of one embodimentof a communication device 74 according to the present invention. Thereis a payload box 300, including an interior container 302 and exteriorStyrofoam insulation 304 surrounding the interior container 302. Withinthe container 302 is a circuit board 306 to which various electroniccomponents are attached and interconnected to provide signalcommunication and remote control of the platform as desired. Theelectronics section consists of the RF section, antennas, GPS receiver,processor and power regulators. The RF section is based on the low costtransmitter and receiver section of current two-way pagers. Thetransmitter power is increased to approximately 7 watts. A single 900MHZ collinear dipole array antenna serves both for transmit and receivefunctions. Additional antennas may be added for gateway RF links to theGround Terminals if the additional frequencies become available.Possible frequencies include the 1680 MHz band assigned tometeorological instruments. If the SNS system also collects weather datafor the NWS and this data is transmitted on the meteorological aidsband, it may be possible to send additional gateway traffic with themeteorological data. A twelve channel GPS receiver in conjunction withthe processor provides positional information to both the NWS duringascent and to the SNS NOC for the entire flight. The NOC uses theinformation to locate the SNS platforms, to determine coverage holes orgaps, and to make rudimentary position adjustments by varying thealtitude into favorable wind speeds and directions.

The embodiment depicted in FIG. 21 and the side partial cross-sectionthereof as depicted in FIG. 22 shows the power for the communicationdevice 74 being provided by a plurality of lightweight, high powerbatteries 308(a), (b), (c) and (d). The platform may require betweenabout three and eighteen watts of power depending on the message trafficand the platform configuration. Lithium sulfur dioxide (LiS02) batteriesare cost and weight effective and have decent operating characteristicsin a low temperature environment as found at high altitudes. Thebatteries are positioned at spaced-apart alternating positions so thatmaximum unit volume density is maintained below established maximum unitvolume density requirements for federal aviation safety standards. Thelow unit volume density and low total payload weight keeps the launchingof the balloons from being restricted by FAA regulations. There is abottom opening 310 through which the meteorological connection cable 84connects at a releasable cable connector 312 to the circuit board 306inside of the container 302. Also, antennae 76 is attached at anantennae connection 314 located in the bottom opening 310 so thatsignals may be received or transmitted through the antennae 76 to andfrom circuit board 306. Meteorological data from fiberoptic cable 84 maybe received and processed in components of the circuit board 306 or maybe transmitted directly to the ground terminal 24 through antennae 76.Active antennae stabilizers 316 are provided to reduce and dampenmovement of antennae 76 so that consistent signal reception andtransmission is accomplished. To facilitate regulation of the altitudeof the airborne platform 12 and the attached communication unit 74, thepayload box 300 includes a ballast storage chamber 320 in which ballast318 is carried. Ballast 318 is preferably easily moveable lead shot,metal BBs or spherical glass beads that may be controllably released aswith a ballast drop gate, such as a shuttle, that moves alternativelybetween opening into the ballast chamber 320 and then to the ballastoutlet orifice 324, such that the ballast may fall from the bottomopening 310 as schematically depicted at 326. For convenience and foravoiding power depletion during storage or transport, a manual circuitactivation switch 328 is provided.

At the top of the payload box 300 is a balloon connection spindle 334,having a distal neck top 332 over which the flexible balloon connectionneck 330 is attached. The balloon connection neck 330 is sized forfitting over the spindle and is stretched and moved down to a stop lip336 so that it is secured in position with one or more heavy rubberbands 338. For convenience, a rubber band storage channel 340 isprovided below the stop lip. A rubber band is stored and in position forsecuring a “fresh,” lighter-than-air enclosure or balloon 70.Preferably, balloon 70 will be filled with helium (He), hydrogen ornatural gas through a light gas fill valve 344 that is preferablypositioned above a rain hood 342 that shields the payload box andcertain components thereof from rain and other precipitation. The lightgas fill valve 344 provides for a convenient connection to a light gassupply tank, such as a helium or a hydrogen supply tank, so that anexpandable balloon is attached at its neck 330 to the spindle 334 andfill gas can then be supplied in a desired amount into the attachedenclosure or balloon. A gas pressure sensor tube 346 communicatesbetween the interior of the spindle to relay the internal balloon gaspressure sensor 348 connected to the electronics of the circuit board. Agas temperature sensor 350 is attached and is desirably positioned at orabove the neck top 332. A temperature sensor wire 352 communicates asignal representing the temperature to appropriate circuitry on thecircuit board 306. An ambient air temperature sensor 354 is alsodesirably provided, as well as an ambient air pressure sensor 356, bothof which are connected for communicating the sensed ambient airtemperature and the sensed ambient air pressure to the circuit board. Abattery temperature sensor 358, a payload temperature sensor 360 and anattitude sensor 362 may all be connected to the circuit board 306 todesirably provide information and input for remote controlling and formaintaining the functions of the airborne platform 12 using the circuit306. The data collected from the gas temperature sensor 350, the ambientair temperature sensor 354, the gas pressure sensor tube input 346, andthe ambient air pressure sensor 356 is used, in part, to determine ifthe balloon is nearing a burst condition. A heater and cooler device 364is attached to control the interior temperature of the payload box. Asthe airborne platform ascends into high altitudes, the ambienttemperature drops dramatically and the interior of the box willdesirably be heated by heat generated by the batteries or,alternatively, by the heater 364. If the heat from the batteries issignificant and is combined with, for example, bright sunlight, theinterior temperature might increase above desired operatingtemperatures, then the cooler portion of heater and cooler device 364may be activated to maintain a desired operating temperature range. Theheater and cooler device may be a thermoelectric cell.

For purposes of regulating the altitude of the balloon and, inparticular, to avoid continuous ascent above the desired maximum highaltitude, a light gas relief valve 366 is provided. A spring 368 keepsthe relief valve 366 normally closed. An actuator rod 369 is attached tothe valve 366 and to a valve actuator wire 370, to open the valveagainst the spring loading. A Nickel-Titanium (NiTi) wire may be used asthe actuator wire 370. Light gas relief valve 366 opens against thespring loading when a small amount of current is passed through the NiTiwire causing it to shrink or shorten a predetermined amount so that therelief valve is pulled open, thereby allowing lighter-than-air gasses toescape. The actuator rod may pass through the top of the container 302,preferably through a seal 371, so that the interior of the container isnot directly exposed to the elements. The ballast shuttle gate 322 maysimilarly be activated with a ballast drop actuator wire 372, also madeof Nickel-Titanium (NiTi). The active antenna stabilizers 316 maysimilarly be comprised of NiTi wire.

A meteorological drop control wire 374 may also be NiTi and can be usedto disconnect the weather sonde after meteorological data is no longerbeing obtained. Typically, weather balloons burst after they passthrough the stratosphere. Here, the balloon will vent some of the lightgas to hold at a stratospheric altitude for desired period of time. Thedestruct mechanism 74 may be remotely activated with the sharp end 378of a pivotal destruct arm to cause the platform to fall. The destructarm 376 is spring-loaded for rapid rotation into contact with theexterior of the balloon when a hold release pin 386 is pulled fromengagement in a hold/release groove 384. The release pin 386 mayadvantageously be controlled with a control wire 388 also appropriatelyactivated through the circuit board upon receipt of remote signalsthrough the antennae 76 or from the processor. Also provided inside ofthe platform is a GPS antennae 390 connected to the circuit board forreception of position information from The GPS satellite system tofacilitate tracking of the platform as it migrates and floats over thecontiguous geographic area of coverage.

FIG. 23 is a schematic side partial cross-section of an alternativeembodiment of the platform according to the present invention in whichthe electrical power source for the communication circuit and controlsis a fuel cell 400. Fuel cell 400 may advantageously be a protonexchange membrane (PEM) fuel cell of the type that uses hydrogen andoxygen to provide electrical power. This type of system requires ahydrogen tube 402 connecting from the source of hydrogen, i.e., thelighter-than-air balloon 70 to the fuel cell 400. A hydrogen inlet 404is provided with a hydrogen circulator 406, which may simply be a fan406. Thus, using the hydrogen tube, hydrogen may be extracted from theballoon and inlet into the fuel cell 400. Also, there is a hydrogenoutlet 408 that is recycled back to the balloon. A hydrogen tubepressure sensor 410 is provided to appropriately monitor the hydrogenpartial pressure at the fuel cell. A fuel cell of this type alsorequires an oxygen supply that may be provided by attaching an oxygenballoon 414 to an oxygen tube 412 so that the oxygen balloon is insideof the hydrogen balloon enclosure. The oxygen balloon is constructed tohold the oxygen at a significant internal pressure. This oxygen balloon414 may be attached to tube 412 with a rubber band 416 and an oxygenpump 418 moves and further pressurizes oxygen from the oxygen balloon414 into the fuel cell through an oxygen inlet 420. Again, to regulatethe process an oxygen pressure sensor 422 is provided. The fuel cellreaction results in water as a byproduct. The water is maintained in aliquid state by the heat generated by the fuel cell and is desirablydrained before it can freeze at the high altitudes at which the platformoperates.

FIG. 24 is a schematic block diagram of the SNS platform hardwarecontained within the payload box 300 and placed on or interconnectedwith circuit board 306. A processor 430 receives electrical signal inputand provides electrical signal output, interacting with a plurality ofcomponents for both controlling the flotation altitude, temperature,balloon destruction, ballast drop, etc. of the platform and also forreceiving, processing and transmitting communication signals receivedand transmitted to and from ground stations, personal communicationdevices or other information communications. Initially, block 432represents either the batteries 308 or the fuel cell 400. Block 434represents the on/off switch 328 to activate providing power to a powersupply regulation circuit 436 with output available power 438. Forclarity, individual power connections to various operational and controldevices have not been shown in all instances. Power is provided to thesupply voltage sensor at block 440 and current supply sensor block 442,which provide information to an analog to digital converter 444. Theanalog to digital converter also variously receives information from thepayload and battery fuel cell temperature gauge at block 446, both gasand ambient air temperature readings at block 448 and gas pressure atblock 450. Additional analog informational signals are generallyrepresented by block 452. Digitally converted information is variouslyprovided to and received from flash memory at block 454 and randomaccess memory (RAM) at block 456. From AID converter 444 and also fromthe flash memory 454 and from RAM memory 456, the processor has accessto all the various input control data. During the ascent of the SNSplatform, the meteorological package represented by block 458 receivesappropriate weather information including ambient temperature 460,ambient pressure at 462 and ambient humidity at 464. The antennastabilization 316 represented by block 496 may rely upon the attitudesensor information that is part of the SNS platform control system at466 to stabilize the antenna 76. Information sensed or gathered by themeteorological package 458 is transmitted. For example, the infraredtransceiver 468 through a fiber optic cable at block 470 correspondingto the physical fiberoptic cable 84 and a processor infrared transceiver472 by which serial meteorological data is transferred to the processor430 for appropriate transmission to ground terminals during the ascentof the SNS platform with the meteorological package 458 attached. A GPSantennae block 474, corresponding to physical GPS antennae 390,communicates through a GPS receiver 476, indicated as a serial port andfurther synchronized with a GPS clock or seconds tick at block 478.Thus, the position at particular times is provided to the processor.This positioning information is coordinated with the othermeteorological input for determining wind speeds steering any part ofthe ascent, thereby corresponding those wind speeds to particularaltitudes and geographical locations during the ascent.

Communications are controlled by processor 430, preferably using both a900 MHZ transceiver and modem 480 and a Gateway transceiver and modem482 signal to and from co-linear array antennae 484 are interfacedthrough a diplexer 486 control information received at co-linear arrayantennae 484, therefore transferred through the diplexer and one of theappropriate frequency transceivers to the processor 430 with inputinformation from ground signals and also from input information from theonboard sensors as provided through AID converter 444, the GPS positioninformation from 476, the GPS time information 478 and the attitudesensor information 466, various functions of the SNS platform can becontrolled. Including the gas vent at block 488 corresponding to the gasvent actuator 370. Also the ballast drop is controlled at block 490corresponding to the physical ballast drop actuator 372. Themeteorological package drop controlled schematically at block 492corresponding to the package drop actuator 374. The balloon destructcontrol is depicted at block 494 corresponding to the destruct actuator376. Antennae stabilization may be affected according to controls atblock 496 corresponding to the antennae stabilization mechanism 316.Payload temperature controls, both heating and cooling, may becontrolled at block 498 corresponding to heaters and coolers 364.Additional functions as may be additionally included, are provided withcontrols at block 500.

One embodiment of this invention relates to a LTA rise rate controlsystem. A typical National Weather Service balloon system, as is wellknown, consists of a rubber extensible balloon filled with a liftinggas, a parachute tied to the balloon, a line extending down from theparachute and a radiosonde tied to the end of that line. The radiosondecollects and transmits weather related data down to a ground station asthe balloon system rises through the atmosphere.

The National Weather Service requires that weather balloons rise at astandard rate of 1000 feet per minute. This is nearly impossible tomaintain throughout the balloon's rise due to many factors including thevariance with altitude of the pressure and temperature of both thelifting gas and the ambient air, the variance in the balloon material,the manufacturing process, and the physical change in the size of theballoon itself as the balloon rises.

In addition, a significant number of NWS weather balloons do not obtainthe desired altitude of 100,000 feet because, among other factors, theballoon expands significantly when obtaining the higher altitudes,becoming thin and many times bursting early for the same reasons aslisted above. If the amount of gas could be reduced at the higheraltitudes, the chance of balloon burst would be decreased.

The present invention utilizes a rise rate control system to vent thelifting gas as needed to slow the balloon's ascent to no more than 1,000feet per minute. Additionally, by venting the lifting gas, the balloonsize is reduced, increasing the probability of reaching the desired100,000-foot altitude without bursting.

The rise rate control system consists of a venting mechanism attached tothe neck of the balloon that can release lifting gas from the balloon, avent actuator for opening and closing the venting mechanism, an altitudesensor for determining the altitude and rise rate of the balloon system,and a comparing mechanism or circuit to control the vent actuator tocause the vent to release some lifting gas when the desired rise rate isgreater than the desired value.

In one embodiment, a GPS unit provides the processor with rise rateinformation. The processor compares the current rise rate with thedesired rise rate stored in the processor's memory. For the NationalWeather Service balloon systems, the desired rise rate is 1,000 feet perminute. If the current rise rate is higher than the desired rise rate,the processor directs the actuator to open the vent until the desiredrise rate is achieved.

Additionally, a ballast system containing a ballast container, ballast,and a ballast actuator could be added to the rise rate control system.The processor compares the current rise rate with a minimum desired riserate stored in the processor's memory. If the current rise rate is lowerthan the desired minimum rise rate, the processor, may activate theballast actuator to drop ballast until the rise rate increases to thedesired value.

The processor may first process the rise rate data coming from the GPSunit by filtering the rise rate values. This filtering may be necessaryas the GPS data may be noisy. Additionally, erroneous data may bepresent and need to be removed from the GPS data. The need for filteringor removing of erroneous data will vary with the different makes andmodels of GPS units. Alternatively, mechanical means for determining therise rate may also be used instead of using rise rate information from aGPS unit.

Another embodiment performs transmitter geo-location from a LTAplatform. Having the capability to locate specific wireless devices canbe extremely valuable. For example, locating a lost semi traileroutfitted with a wireless locating device could save a trucking companymany thousands of dollars. Locating a wireless caller experiencing anemergency could save the caller's life by appropriately directingemergency services. Many wireless device manufacturers are incorporatingGPS into their devices but for many devices this is not yet appropriatedue to cost, size, battery power demands, the poor signal penetration ofGPS in the operating environment, or other factors. Legacy devices willcontinue to exist in the marketplace that do not have the capability toprovide their own location.

This invention provides a method of gee-locating a received signal byutilizing signal path delay measurements taken from one or more freedrifting, high altitude lighter-than-air platforms. The method has thefollowing advantages: The invention does not require the wireless devicethat it is tracking to contain position determining circuitry such asGPS thereby reducing the size, cost, weight and power of the mobiletransmitter. It works with currently available wireless devices such aswireless phones, two-way pagers, advanced messaging devices, wirelessInternet access devices, and almost any wireless information accessdevice to add location capabilities without requiring modification. Ithas higher accuracy than solely using the knowledge of which tower ortowers are currently receiving the mobile transmitter signal even withthe use of sectored antennas. It does not require specializeddirectional antennas. Extremely large coverage areas can be providedfrom a single receiver.

The present invention utilizes multiple signal path delay measurementsby high altitude platforms of the received signal from a wireless deviceto determine the wireless device's position. This method can either beused to locate wireless devices registered on a network supplied by thehigh altitude platform, or to provide or supplement the locationcapabilities of existing terrestrial based wireless networks of wirelessdevices registered on their network. In the later case, the highaltitude platform needs only to measure the signal path delay of thewireless device and does not need to decode the wireless device'straffic.

This invention works with wireless transmitters whose transmissions aretime synchronized to a standard. This standard may be GPS time or thetiming of the network that the received wireless device is registeredon. In most situations, the timing comes from the platform's forwardchannel transmission to the wireless device. In this case, all wirelessdevices on the platform's network have their timing synchronized withthe received transmissions from the platform. The wireless device thenuses this timing for transmissions back to the platform. Because ofthis, the start of a signal received at the platform from a wirelessdevice is delayed by twice the signal path delay of the distance betweenthe platform and the wireless device (FIG. 25). This signal path delayis measured by the platform and later converted to a distance. Thedistance from the platform to the wireless device is roughly Distance inmeters=300,000,000*measured signal path delay in seconds/2.

If the platform uses a non directional antenna and the wireless deviceis on the ground, a rough circle can be traced on the surface of theearth with the platform as the center of the circle. The radius of thecircle is the distance from the platform to the wireless device. Thewireless device is located on this circle (FIG. 26). As the trace is theintersection of the surface of the earth with a measured distance fromthe platform (the distance calculated from the signal path delay), andthe earth's terrain is not spherical, the trace does not form an exactcircle.

A platform in a different position above the earth receiving the signalfrom the same wireless device also measures a signal path delay. Thisdelay is also converted to a distance and can roughly trace out a circledrawn on the surface of the earth of the possible locations of thewireless device as described above. Again, this does not form an exactcircle due to the earth's terrain. The intersections of these two roughcircles give the two potential locations of the wireless device (FIG.27).

A third position of a platform receiving the signal from the samewireless device also measures a signal path delay. This delay is alsoconverted to a distance and can roughly trace out a circle drawn on thesurface of the earth of the possible locations of the wireless device.Again, this does not form an exact circle due to the shape of the earthand varying terrain. The intersections of this circle with one of thetwo points from the prior intersection finally determines the locationof the wireless device.

The geo-location of a wireless device, as described above, requiresthree measurements from a platform or platforms. The primary requirementis that the platform position be different for each measurements toallow the circles to form points at the intersections. It is possible touse a single platform taking measurements at three different positionsas the platform moves. It is best if the three measurements be taken asclose in time to each other as possible or practical to reduce thechance that the wireless device has moved between measurements. Themeasurements do not need to be taken simultaneously as is the case withother geo-location methods.

Although the single platform taking three separate signal path delaymeasurements has the potential to be the least accurate due to movementof the wireless device, it does not tie up the resources of otherplatforms to locate one wireless device. This is especially true whenthe wireless device is using a platform to supply its network.Therefore, the most preferred embodiment is that of the single platformgeo-location.

Although three separate signal path delay measurements are necessarymathematically to determine the position of a wireless device on thesurface of the earth, two measurements may be sufficient if the wirelessdevice is known to stay in an area on the earth that is small relativeto the distance between the two points acquired from the intersection ofthe first two signal path delay measurements. The wireless devicelocation can be assumed to be the point closer to the usual or knownmost recent location of the wireless device.

Using sectored or directional antennas on one or more of the platformsperforming the measurements may reduce the number of measurements neededto two. For example, if two separate measurements are taken from aplatform or platforms with a 3-sectored antenna, the circles traced onthe surface of the earth are reduced to 120-degree arcs. In a majorityof the cases, the two arcs will only intersect at one point, that pointbeing the location of the wireless device.

Satellite and terrestrial systems also employ various forms ofgeo-location although the methods are different. Satellite systemsgenerally either have GPS units onboard the wireless device and do notneed to geo-locate the device or they utilize Time Difference Of Arrival(TDOA) calculations to obtain the wireless device location. Timedifference of arrival requires that more than one satellite receive thewireless device's signal simultaneously. Also, satellite systemsemploying geo-location techniques can rely on ephemeris data tocalculate the location of the satellite. This mathematical method ofdetermining location is not available to free drifting platforms andtherefore an additional sensor such as GPS is required to determine theplatforms position. Low earth satellite systems travel at significantspeeds with respect to the earth (generally over 17,000 mph) andtherefore must account for Doppler in their techniques. The presentinvention is moving at such a rate that Doppler adjustments are notnecessary (under 100 mph). Terrestrial systems such as the various voicenetworks, do not need to sense the receiver position as the towers usedare fixed. Nor do terrestrial systems require that ability to updatetheir terrain maps when calculating the position of the wireless deviceas the terrain does not vary for that tower. The present invention mustdo both of these as it free drifts with the wind. An advantage of thepresent advantage is that excessive signal filtering is generally notrequired on a free drifting platform in order to perform thegeo-location since there are no near, overpowering transmitters as therecan be for terrestrial receivers. Reducing the amount of filtering onthe receiver can mean a significant reduction in both size and weight ofthe required hardware.

The geo-location system consists of a ground network, one or more highaltitude, LTA platforms, and wireless devices located on the ground. Theground network consists of a receiver capable of receiving signal pathdelay measurement information from a high altitude, LTA platformwirelessly, and at least one processor that can receive the data fromthe receiver. The processor is capable of calculating distance frommultiple signal path delay measurements, calculating distance vectorsonto terrain maps to determine distance circles, and determiningintersections of circles and points on a terrain map to determine thelocation of a wireless device.

The high altitude, lighter-than-air platform consists of a receivercapable of receiving a signal from a wireless device, a GPS unit capableof providing position and timing information, and a processor capable ofmeasuring the difference between a timing standard and the receivedsignal from the wireless device, a wireless data link from the platformto a ground network to allow the receiver to send the signal path delayrelated information and platform position to the ground network.

The wireless device synchronizes its timing to either GPS, the receivedforward channel from the platform or from the terrestrial network thewireless device is registered on. The receiver on the platform receivesframes transmitted from the wireless device. The processor compares thearrival time of the received frame from the receiver to the referencetiming of the appropriate network or GPS to obtain the signal pathdelay. The processor sends the calculated signal path delay and thecurrent platform location over the wireless data link to the groundnetwork. The ground network converts the signal path delay to distanceand calculates a rough circle on the surface of the earth using thecalculated distance to the wireless device as the radius and theposition of the platform as the center of the circle. This circle isrough in shape due to the earth's terrain. The wireless device locationlies somewhere on this circle. A platform at a second position performsthe same operation on the same wireless device to calculate a secondrough circle on the earth. The intersection of these two circles formstwo points on the earth's surface. A platform at a third position,again, performs the same operation on the same wireless device tocalculate a third rough circle on the earth which intersects one of thetwo points from the previous intersection. That point is the location ofthe wireless device.

[When the platform is locating a wireless device registered on aterrestrial network, the platform's ground network must have access tothe timing standard used by the terrestrial network as well as thelocation of the tower the wireless device is communicating with in orderto measure the signal path delay as this delay includes the signal pathdelay of the transmission from the network tower to the wireless deviceas well as the signal path delay from the wireless device to theplatform. In this case, the roughly circular trace that the wirelessdevice is located on becomes an ellipse with the platform and theterrestrial towers as the focal points of the ellipse. As the platformis at a significant altitude and has a large coverage area in which itcan receive signals, when there is a need to locate a wireless devicethat is registered on a terrestrial network, it is desirable to have theterrestrial network command the wireless device to switch to a less usedor dedicated frequency. This reduces or eliminates the number ofreceived signals seen by the platform when the signal path delaymeasurements are made.

Depending on the protocol and frame structure used by the wirelessdevice, the best feature of the frame to make the timing measurement offof may vary. The feature may be the start of a bit or a phase,frequency, or even amplitude change.

The major sources of error when using signal path delay measurements forgeo-location come from the wireless devices themselves particularly inthe capability of the wireless device to accurately match the timing oftheir transmissions with the received network timing. Half duplexdevices have a much more difficult time accurately timing theirtransmissions to the forward channel as they must maintain the systemtiming internally between receiving and transmitting. A significantadditional source of error comes from the timing resolution of theplatform's receiver. For example, if the timing measurement resolutionof the platform's receiver is 100 ns, that translates to a error of upto 300000000*0.0000001/2 or 15 meters of distance error.

Preferably, the LTA platform system of this invention is free-floating,moves at a speed of less than 100 miles per hour, more preferably, lessthan 50 miles per hour, and floats at an altitude of between60,000-140,000 feet above the surface of the earth. Also, thegeo-location system of this invention does not require that the LTAplatforms do not need to account for Doppler shift unlike low earthorbit satellites.

Most scientific, commercial, and other ballooncraft payloads are worththe additional cost of recovering them. The largest problem withrecovering payloads is knowing the actual landed location. Inmostsituations, contact with the payload is lost when the payload fallsbelow the horizon from the ground station and line of sightcommunications are lost. The landed location of payload can only beestimated. If communication with the payload is lost at a relativelyhigh altitude, the payload may drift a significant distance as itdescends and finding the payload's landed location becomes difficult.Satellite telemetry devices have been placed on payloads to solve thisproblem but remain a costly option. The weather services around theworld currently launch approximately 800,000 radiosondes each year. Onlyabout 18% of these radiosondes are recovered, reconditioned andreclaimed. The National Weather Service has no way of locating them onceon the ground. A method of locating these payloads would significantlyreduce the number of non-recovered payloads littering the ground.

The present invention uses a low cost transmitter to send the GPSposition of a landed payload to a second, aloft ballooncraft for relayto a ground station to aid in recovery or to confirm the landing site.The electronics for such a system are much less complex and costly thanthat of a satellite telemetry unit as the design does not need toincorporate processing for large Doppler shifts. Also, the secondballooncraft is significantly closer to the landed payload than even alow earth orbit satellite and therefore the location transmitting deviceon the landed payload requires less transmit power than that needed tocommunicate with a satellite.

The location transmitting device on the payload consists of a GPS unitcapable of supplying position data, a transmitter capable oftransmitting data in a desired protocol such as FLEX or POCSAG on adesired frequency such as the NPCS frequencies, a processor capable ofreading data from the GPS unit and sending data to the transmitter fortransmission, and a power supply capable of supplying power to the GPSunit and the transmitter. The processor is connected to the GPS unit inorder to receive position and timing data. The processor is connected tothe transmitter to enable the processor to send data wirelessly to thesecond, aloft ballooncraft. The power supply is connected to supply boththe transmitter and the GPS unit with power.

The processor receives position data from the GPS unit. In order todetermine if the payload has landed or is close to landing, theprocessor looks for at least two conditions. The first condition is thatthe payload is not changing position (including altitude). Filtering theGPS position and altitude data may be necessary to allow thisdetermination. The amount of filtering necessary depends on the actualGPS unit used as some units supply filtered position data. The secondcondition is that the altitude of the landed payload is determined to bebelow a stored value such as 15,000 feet. As most ballooncraft missionsoperate above 60,000 feet, this prevents the location-transmittingdevice from transmitting during normal operation. Other conditions maybe added to assure that the payload has landed before transmissionstarts. When the processor has determined that the payload has landed,the processor reads the current GPS position and sends it to thetransmitter for transmission to the second, aloft ballooncraft. Theprocessor continues to send the position data to the transmitter at setintervals such as once every 30 minutes. The second, aloft ballooncraftreceives the position transmission and relays the information to itsground station to aid in recovery or confirm the landing site as isshown in FIG. 9.

In an alternate embodiment, the transmitter is replaced with atransceiver capable of operating in a desired 2-way protocol such asReFLEX, GSM, CDMA, or iDEN on a desired frequency such as the NPCS orBPSC frequencies. When the ground station wishes to determine theposition of the landed payload, and a second, aloft ballooncraft iswithin communications range of the landed payload, the ground stationsends a request to the location transmitting device transceiver throughthe second, aloft ballooncraft. The processor receives the request,queries the GPS for position and sends the position data to thetransceiver for transmission to the second, aloft ballooncraft for relayto its ground station to aid in recovery or confirm the landing site asis shown in FIG. 9.

Alternately, the transmitter could utilize a low power unlicensedfrequency.

A device such as the CreataLink 2XT from SmartSynch, Inc. has anprocessor integrated with a ReFLEX transceiver. This device could beused in place of a separate transceiver and processor.

If the mission of the second, aloft ballooncraft is providing service asa wireless network for wireless devices such as ReFLEX telemetry unitsor digital phones (using iDEN, CDMA, GSM, or other digital protocolsused for voice services), the landed payload can operate as anotherwireless device on the ballooncraft wireless network. This allows thelanded payload to perform its function of reporting its location to theground station by acting simply as another wireless device on thesystem. The landed payload could then send a message or place a call tothe ground station to provide its location as another wireless deviceoperating on the ballooncraft's service.

To reduce cost and complexity, an existing processor already on thepayload that is performing other functions during the flight, but isidle now that the flight is over could do the processing functionsdescribed above in order to save costs. The power needs of thelocation-transmitting device could also be provided by the payload'sexisting power supply.

Another preferred application of the geo-location system and method ofthis invention is usage monitoring and determining the location ofground-based vehicles, particularly semi trailers. Knowing the locationand movement of semi trailers can significantly reduce the cost ofsearching them when they are stolen or simply misplaced. It is alsoimportant to know when the trailers require periodic maintenance. Thetrucking industry has utilized mechanical tire rotation counters mountedto the hub of trailers to measure the distance traveled by the trailersprimarily for maintenance purposes but these have to be manually read.This invention provides a low cost, wireless means for remotelymonitoring semi trailer location and usage information.

The present invention utilizes a GPS unit, a processor, a wirelesstransceiver, a power source, and a tire rotation sensor mounted in aweatherproof housing attached to the hub of a semi trailer wheel for thepurpose of measuring the current speed, distance traveled, location andother usage related values of the semi trailer and wirelessly transmitthis information back to a host office through a wireless network eitherautomatically or upon request.

In its preferred embodiment, a tire rotation sensor, a transceiver, apower source, a processor, and GPS unit are located within aweatherproof housing that is rotatably attached to the hub of a vehiclewheel (FIG. 28). The weatherproof housing does not rotate with the wheelas it is rotatably attached to the wheel and is weighted to maintain anupright position at all times.

The processor is connected to the output of the tire rotation sensor andcan communicate with the GPS unit for the purpose of receiving position,speed, direction, and timing information from the GPS unit. Theprocessor is also connected to the transceiver in order to exchange dataand commands wirelessly through the network with the host office. Thepower supply provides power for the GPS, processor and tire rotationsensor. The power supply may be batteries, solar cells mounted on theweatherproof housing so as to be visible externally, a generator thatutilizes the rotation of the wheel with respect to the housing togenerate electricity or, most likely, a combination of the three. Ifeither the solar cells or the generator are used, the batteries must berechargeable. If rechargeable batteries are used, a charging circuitreceives power from the generator or the solar cells and charges therechargeable batteries with this power appropriately. The generator ismounted in the weatherproof housing and attached to the hub such thatwhen the vehicle is moving, the generator shaft is turned. The solarcells when sunlight is available and the internal generator when thevehicle is moving, provide power to charge the internal rechargeablebatteries through the charging circuit. The processor removes power fromthe GPS or places the GPS in low power mode when the GPS is not in useto reduce power consumption. The processor may also put itself into alow power mode that wakes up when the tire rotation sensor sensesmovement, a query comes from the host office through the transceiver, ora timed interval has elapsed.

In operation, the processor monitors the tire rotation sensor todetermine vehicle speed and distance traveled. The processor queries theGPS unit to determine vehicle position if significant tire rotationshave occurred or when queried by the host office. Values such as thesemi trailer's maximum speed, total distance traveled, and totaltraveling time are stored in the processor's non-volatile memory fortransmission. Alternately, the tire rotation sensor can be removed andspeed and distance may be computed by the processor using GPS data suchas heading, speed, and position.

[Upon request from the host office, at scheduled intervals, or atspecific events such as when the vehicle starts moving or when thevehicle leaves a specific geographical area, the processor sends therequired values to the wireless transceiver for transmission to the hostoffice. The transceiver communicates with the host office over a ReFLEX,CDPD, GSM, CDMA, TDMA, iDEN™, or other selected network. The transceivermay be replaced with a transmitter if the network used does not requirea device to have a receiver in order to operate on the network. FLEX andPOCSAG networks are examples of this.

Yet another embodiment of this invention is a steerable recovery systemthat is applicable for autonomous, GPS guided parachutes and gliders.Steerable parachutes and gliders are important for the recovery ofexpensive payloads, safely avoiding populated areas during descent, andfor specific target delivery applications. Generally, the controlsystems for these steerable recovery systems are not designed for lowcost as the payloads themselves are very expensive and the controlsystem is a fraction of the overall cost. Recent, high volume, low costballooncraft applications have made a simplified, lower cost controlsystem more important. This invention reduces the overall cost of anautonomous steerable recovery system by utilizing novel algorithms thatallow operation without the need for a compass and airspeed indicator.This invention has applicability in the scientific, meteorological,commercial, and other fields.

Steerable recovery systems require five inputs: (1) the current positionof the steerable body; (2) the target position where the steerable bodyshould land; (3) the ground track vector; (4) the local wind vector; and(5) the flight vector. The three different vectors are used in thecontrol of an autonomous steerable recovery system, the Ground trackvector which is the direction and speed that the Recovery system ismoving with respect to the earth's surface, the Local wind vector whichis the direction and speed of the wind at the Recovery system withrespect to the ground, and the Flight vector which is the direction andspeed the Recovery system is moving with respect to the local air at therecovery system. Typical autonomous, GPS guided recovery systems use GPSto provide the Ground track vector. An onboard compass supplies theFlight vector direction, and the flight vector speed is either providedby a pitot tube or by estimating the forward travel from the glide ratioand current fall rate. With these two vectors, the Local wind vector canbe determined as the Ground track vector is the sum of the winds actingon the Recovery system (Local wind vector) and the speed and directionin the local air of the Recovery system (Flight vector).

This invention relating to steerable recovery systems can be summarizedas follows with reference to FIGS. 29-33. A GPS supplies the Recoverysystem's current position and Ground Track vector. The Ground trackvector is measured before starting the turn so that it is measured innon-turning flight (FIG. 29). In present systems, a compass is used todetermine the Flight vector's direction and the Flight vector's speed iseither calculated from the descent rate and the estimated glide ratio ofthe Recovery system or by using an airspeed sensor (FIG. 30). Themeasured Flight vector is one of the two components that sum together toform the Ground Track vector (FIG. 31). The second component, the Localwinds vector, is determined by subtracting the measured Flight vectorfrom the Ground track vector. In the present invention, the Local windsvector is determined by effectively nullifying the Flight vector andcalculating the new Ground Track vector over the period of time theFlight vector is nullified. In order to null the Flight vector, theRecovery system is placed into a constant turn for one full revolution.If no local winds are present (Local vector equals zero), the path ofthe Recovery system with respect to the ground is a circle (FIG. 32).Over the total period of time of the turn, the effective Ground trackvector is zero as the Recovery system ended up in the same position inlatitude and longitude that it started. Since the Ground track vectorwas measured to be zero during the turn, the winds are calculated to bezero since the Ground track vector equals the sum of the Local windsvector and the Flight vector and the Flight vector was nullified byturning in a circle over the period of the turn. If local winds arepresent, the path of the Recovery system is a circle shifted by thelocal winds. In the following example, the Local Winds vector is fromthe west (heading 90 degrees) (FIG. 33). The path of the Recovery systemduring the complete circle is pushed to the East by the Local windvector. The path of the Recovery system (above) shows how the start andend positions of the circle are shift by the local winds. By measuringthe start and end positions during the turn and dividing by the time ittook to complete the full circle, the Local wind vector is determined.Subtracting the Local winds vector from the Ground track vector taken inlevel flight (before the start of the turn) the Flight vector isdetermined. By the steering method of this invention, the payload of thesteerable recovery system need not have a compass and air speedindicator, which are required in conventional systems to determine theFlight vector.

GPS is unable to provide the Flight vector direction because GPS'sposition and Ground track vectors are in relation to the earth's surfaceand give no information as to the Recovery System's flight through theair around it. The Recovery systems flight direction is in reference tothe local air. For example, if the Recovery system is facing west with aairspeed of 40 mph and the wind speed is 60 mph toward the East, GPSwill provide a Ground Track vector of East at 20 mph although thesteerable system is actually facing West. This is why a compass isnecessary to provide the actual direction the Recovery system is facingand not the direction the recovery system is moving with respect to theground. For the same reasons given above, the Flight vector speed mustalso be determined from sources other than the GPS as the Flight vectorspeed is the airspeed and not the Ground track speed. Therefore it isnecessary either to have an airspeed sensor on the Recovery system or toestimate the Flight vector speed from the Recovery system's glide ratio.

Since the Ground track vector is the sum of the Local winds vector andthe Flight vector, if the Flight vector can be removed or nullified,then the Local winds vector becomes equal to the current Ground trackvector. This invention nulls both the direction and speed of theRecovery system through the local air (the Flight vector) by flying theRecovery system in a complete circle and measuring the Ground trackvector over the interval. As there is no compass on board the Recoverysystem, one complete turn is determined by monitoring the Ground trackvector direction. When the vector matches that recorded at the start ofthe turn, one full turn is complete. Over the period of time it takes tomake the full circle any component of the Flight vector is removed as itaverage out to zero. Therefore, the only lateral force on the Recoverysystem is the wind. By taking the change in position over the total timeto loop, the Local wind vector is determined. The Flight vector can thenbe determined by subtracting the Local wind vector from the Ground trackin level flight. The calculations involved in determining the Local windvector (direction and speed) as well as the Flight direction vectorfollow.

Make the following measurements during flight in order to null thecontributions of the Flight vector:

-   -   Place the steerable parachute or glider into a constant rate of        turn. The speed of the turn is not critical although the rate        should be chosen to minimize the altitude change during the        complete turn. This minimizes the error due to changes in the        Wind vector with altitude. It is important that the turn rate be        as constant as possible.    -   Record the Ground vector, position, and time.        -   Start Ground Vector direction (degrees)        -   Start Ground Vector speed (m/s)        -   Start latitude (decimal)        -   Start Longitude (decimal)        -   Start Time (GPS seconds)    -   Continue the turn until the ground vector direction matches that        recorded at the start of the turn    -   Record the current ground position, and time.        -   End latitude (decimal)        -   End longitude (decimal)        -   End Time (GPS seconds)    -   Calculate the Local wind vector and the Flight vector using the        method and formulas below.    -   To return to the original direction, roll out of the turn and        adjust direction to maintain the initial Ground track vector        direction.    -   To continue turning to a new Flight vector direction continue to        turn the number of seconds calculated below before rolling out        of the turn.

Number of additional degrees of turn desired*(End_Time−Start_Time)/360

-   -   Alternately, the appropriate Ground track vector direction can        be calculated from the newly calculated Local wind and Flight        vectors.

Taking the end measurements when passing through the exact heading asthat of the start measurements allows the measurement period to be thatof one complete turn. By flying the recovery system in a constant,complete circle any component of the Flight vector is removed from theGround track vector for the period from Start Time to End Time. The onlylateral force on the Recovery system is the Local wind. By taking thechange in position over the total time to complete a full turn, theLocal wind vector is determined.

The latitude and longitude change during one complete turn due to thelocal winds are calculated as follows:

Latitude_change_(radians)=[Start_latitude_(decimal)−End_latitude_(decimal)]*pi/180

Longitude_change_(radians)=[Start_longitude_(decimal)−End_longitude_(decimal)]*pi/180

Converting latitudinal and longitudinal change during one complete turnto the Local wind North and East components in meters per secondrequires the non-spherical earth model to convert latitudinal andlongitudinal change to actual distances and rates. The formulas can besummarized as:

Radius of the Earth atlatitude(Rn)=Ravg/(1−Eccent*(sin(latitude_change_(radians))̂2))

Where Ravg is the average radius of the earth=6378137 meters and Eccentis the earth's eccentricity=0.00669437999014138

Local_Winds_North_(m/s)=Rn*Latitude_change_(radians)/(End_Time−Start_Time)

Local_Winds_East_(m/s)=Rn*cos((Start_Latitude_(decimal)+End_Latitude_(decimal)/2)*pi/180)*(Longitude_change_(radians)/(End_Time−Start_Time)

Convert the Local wind components to a vector (Local winds vector).

Local_winds_direction_(degrees)=ArcTAN(Local_winds_North_(m/s)/Local_Winds_East_(m/s))

If the Local Wind direction is negative, add 360 degrees.

Local_winds_speed_(m/s)=SQRT((Local_Winds_North_(m/s))̂2+(Local_Winds_East_(m/s))̂2)

From the Ground track vector from GPS and the Local wind vector, theFlight vector can be determined. It is easier to subtract the Local windvector from the Ground track vector when both vectors are converted toNorth and East components first:

Convert the Ground track vector to its North and East components.

Ground_Track_North_(m/s)=cos(Start_Ground_Vector_Direction_(degrees)*Pi/180)*Start_Ground_Vector_Speed_(m/s)

Ground_Track_East_(m/s)=sin(Start_Ground_Vector_Direction_(degrees)*Pi/180)*Start_Ground_Vector_Speed_(m/s)

Subtract the Local wind components from the Ground Track components toarrive at the Flight components.

Flight_North_(m/s)=Ground_Track_North_(m/s)−Local_Winds_North_(m/s)

Flight_East_(m/s)=Ground_Track_East_(m/s)−Local_Winds_East_(m/s)

Convert the Flight components to a vector (the Flight Vector).

Flight vector direction(degrees)=ArcTAN(Flight_North_(m/s)/Flight_East_(m/s))

If the Flight direction is negative, add 360 degrees.

Flight vector speed(m/s)=SQRT((Flight_North_(m/s))̂2=(Flight_East_(m/s)̂2)

Now the Flight vector and the Local wind vector have been separated fromthe Ground track vector and the steering control algorithms can usetheir components.

The software functions above can be implemented into the control systemof an autonomous Recovery system such as an autonomous, GPS guided,steerable parachute or glider. A typical system consists of at least thesteerable parachute or glider, one or more steering actuators, a GPSunit for position data, ground track, and time, a processor to performthe algorithms described above, and a power source for the processor andactuators. No airspeed sensor or compass is needed.

A steerable parachute includes steering control lines that are pulled orreleased to effect a turn of the Recovery system. A steering actuatorsuch as a winch, could turn one way to pull the right turn steeringcontrol line and turn the other way to pull the left turn steeringcontrol line. The processor controls the actuator to steer in eitherdirection. The processor receives the Ground track vector, positiondata, and time from the GPS unit. The processor initiates a completecircle as described above, receives information from the GPS and appliesthe algorithms described above to determine the current Flight and Localwinds vectors. The processor then controls the actuators appropriatelyto end or continue the turn based on its steering algorithm in order tonegotiate to the target landing position.

A single control line may also be used to steer the parachute. Thisallows the parachute to turn primarily in only one direction (directionA). The parachute would either be turning in direction A or adjusted tostraight flight by the actuator under processor control (by maintaininga constant Ground track direction). The steerable parachute would bedesigned to have a natural inclination to turn slightly in the oppositeof direction A (direction B) when the steering line is completely slack.Slightly adjusting (pulling) the control line would cause the parachuteto fly straight as indicated to the processor by a constant Ground trackdirection. Further pulling the control line would cause the parachute toturn in direction A. This capability to trim the parachute for straightflight is generally necessary to correct for individual differences inthe parachutes.

Because the local winds may change as the Recovery system descends intodifferent winds, the Flight and Local wind vectors will occasionallyneed to be recalculated to account for both the new Local winds and thechange in the Flight vector due to changes in air density and otherfactors. There may be additional error due to differing winds betweenthose at the start measurements and those at the end measurements. Thefull circle procedure described above should be done as often asnecessary for the desired accuracy of the Flight vector. The majordrawback to performing the full circle procedure more frequently is thatthe effective forward motion of the Recovery system is not availablewhile in the full circle procedure.

An example of the inventive method being used to determine Local windand Flight vectors without the use of a compass or airspeed indicator isshown in Table 1.

Other alterations and modifications of the invention will likewisebecome apparent to those of ordinary skill in the art upon reading thepresent disclosure, and it is intended that the scope of the inventiondisclosed herein be limited only by the broadest interpretation of theappended claims to which the inventors are legally entitled.

1. A method to determine a location of a device transmitting wirelesssignals to a plurality of lighter-than-air (LTA) platforms, the methodcomprising taking signal path delay measurements from the plurality ofLTA platforms; determining the location of the device transmittingwireless signals based on the signal path delay measurements; andcommunicating the location of the device transmitting wireless signalsto an LTA platform.
 2. The method of claim 1, wherein one or more of theplurality of the LTA platforms float at an altitude of about60,000-140,000 feet.
 3. The method of claim 1, wherein one or more ofthe plurality of the LTA platforms have a speed relative to the surfaceof the earth of less than 100 miles per hour.
 4. The method of claim 1,wherein the signal path delay measurements are performed by measuringthe difference between a time of arrival of a wireless signal of thedevice transmitting wireless signals and a standard time.
 5. The methodof claim 1, wherein the determining the location of the devicetransmitting wireless signals is based on the signal path delaymeasurements from at least three independent LTA platforms.
 6. Themethod of claim 1, wherein the device transmitting wireless signals islocated (a) on an LTA platform that has landed on the earth, or (b) on aground-based vehicle.
 7. The method of claim 1, wherein the devicetransmitting wireless signals includes a radiosonde.
 8. The method ofclaim 1, wherein the device transmitting wireless signals includes alanded payload.
 9. The method of claim 8, wherein the devicetransmitting wireless signals includes a payload that has landed on theearth.
 10. The method of claim 9, wherein the determining that thedevice transmitting wireless signals has landed on the earth compriseschecking for no shifting of the location of the device transmittingwireless signals.
 11. The method of claim 1, wherein the determining thelocation of the device transmitting wireless signals based on the signalpath delay measurements comprises: determining distances from the deviceto the plurality of LTA platforms; tracing out approximate circles onthe earth based on the distances; and determining a point ofintersection of the circles, wherein the point of intersection issubstantially the location of the device transmitting wireless signals.12. The method of claim 11, wherein the taking signal path delaymeasurements is taking only two signal path delay measurements.
 13. Themethod of claim 11, wherein the taking signal path delay measurements isperformed using sectored or directional antennas.
 14. A method todetermine a location on the earth of a device transmitting wirelesssignals comprising a GPS unit, the method comprising: measuring alocation of the device transmitting wireless signals by the GPS unit;determining that the device transmitting wireless signals is stationaryon the earth; and communicating the location of the device transmittingwireless signals to a lighter-than-air (LTA) platform.
 15. The method ofclaim 14, wherein the LTA platform floats at an altitude of about60,000-140,000 feet.
 16. The method of claim 14, wherein the devicetransmitting wireless signals includes a payload that has landed on theearth, and the determining comprises determining that the devicetransmitting wireless signals has landed on the earth.
 17. The method ofclaim 16, wherein the determining that the device transmitting wirelesssignals has landed on the earth comprises checking for no shifting ofthe location of the device transmitting wireless signals.
 18. The methodof claim 14, wherein a device transmitting wireless signals includes aradiosonde that has landed on the surface of the earth.
 19. The methodof claim 14, wherein the device transmitting wireless signals is located(a) on an LTA platform that has landed on the earth, or (b) on aground-based vehicle.
 20. The method of claim 19, wherein theground-based vehicle comprises a housing attached to a hub of theground-based vehicle, wherein the housing comprises a tire rotationsensor.
 21. A method to determine a location of a device transmittingwireless signals to one or more (LTA) platforms, the method comprising:taking signal path delay measurements from an LTA platform at differentintervals of time; determining the location of the device transmittingwireless signals based on the signal path delay measurements; andcommunicating the location of the device transmitting wireless signalsto the LTA platform.
 22. The method of claim 21, wherein the signal pathdelay measurements at different intervals of time from only one LTAplatform.
 23. The method of claim 21, wherein the device transmittingwireless signals includes a radiosonde.
 24. The method of claim 21,wherein the device transmitting wireless signals includes a landedpayload.
 25. The method of claim 21, wherein the device transmittingwireless signals includes a payload that has landed on the earth. 26.The method of claim 25, wherein the determining that the devicetransmitting wireless signals has landed on the earth comprises checkingfor no shifting of the location of the device transmitting wirelesssignals.
 27. The method of claim 21, wherein the signal path delaymeasurements are performed by measuring the difference between a time ofarrival of a wireless signal of the device transmitting wireless signalsand a standard time.
 28. The method of claim 21, wherein the devicetransmitting wireless signals is located (a) on an LTA platform that haslanded on the earth, or (b) on a ground-based vehicle.
 29. The method ofclaim 21, wherein the determining the location of the devicetransmitting wireless signals based on the signal path delaymeasurements comprises: determining a first distance from the device tothe LTA platform at a first time instance; tracing out a firstapproximate circle on the earth based on the first distance; determininga second distance from the device to the LTA platform at a second timeinstance; tracing out a second approximate circle on the earth based onthe second distance; and determining a point of intersection of thefirst and second approximate circles, wherein the point of intersectionis substantially the location of the device transmitting wirelesssignals.
 30. The method of claim 21, wherein the taking signal pathdelay measurements is performed using sectored or directional antennas.